Online Etymology Dictionary

commuter (n.): 1865, American English, "holder of a commutation ticket," agent noun from commute (v.).
Como: lake in Italy, named for the town along its shore, which is Roman Comum, from Celtic cumba "valley" (cf. coomb). Its ancient name was Lacus Larius; Lacus Comacinus begins to appear 4c. It is associated with Virgil and the two Plinys.
comorbidity (n.): 1985, from co- "along with" + morbidity "diseased condition." Comorbid (adj.) is a 1990 back-formation.
comp (n.): "complimentary ticket," 1885, short for complimentary. Meaning "nonpaying guest" is attested by 1930s; generalized to "anything given free" by 1960s. As a verb, by 1974. Related: Comped; comping. As a shortening of compensation (especially worker's/workman's) it was in use by 1970s.
compact (adj.): late 14c., from Middle French compact (14c.) or directly from Latin compactus "concentrated," past participle of compingere "to fasten together, construct," from com- "with, together" (see com-) + pangere "to fix, fasten" (see pact). Compact car is 1960. Compact disc is from 1979.
compact (n.1): "agreement," 1590s, from Latin compactum "agreement," noun use of neuter past participle of compacisci "come to agreement," from com- "together" (see com-) + pacisci "to covenant, contract" (see pact).
compact (v.): early 15c., from Latin compactus, past participle of compingere "to fasten together" (see compact (adj.)). Related: Compacted; compacting.
compact (n.2): "make-up case," 1921, from compact (adj.), based on its containing compacted face powder.
compaction (n.): late 14c., from Old French compaction, from Latin compactionem (nominative compactio) "a putting or joining together," noun of action from past participle stem of compingere (see compact (adj.)).
compadre (n.): "companion," 1834, American English, from Spanish compadre "godfather," hence "benefactor, friend," from Medieval Latin compater, from com- "with" (see com-) + pater "father" (see father (n.). Cf. compere, also gossip (n.).
companion (n.): c.1300, from Old French compagnon "fellow, mate, friend, partner" (12c.), from Late Latin companionem (nominative companio), literally "bread fellow, messmate," from Latin com- "with" (see com-) + panis "bread" (see food).

Found first in 6c. Frankish Lex Salica, and probably a translation of a Germanic word (cf. Gothic gahlaiba "messmate," from hlaib "loaf of bread"). Replaced Old English gefera "traveling companion," from faran "go, fare."
companionable (adj.): 1620s, from companion + -able. Related: Companionably; companionability.
companionship (n.): 1540s, from companion + -ship.
company (n.): mid-12c., "large group of people," from Old French compagnie "society, friendship, intimacy; body of soldiers" (12c.), from Late Latin companio (see companion). Meaning "companionship" is from late 13c. Sense of "business association" first recorded 1550s, having earlier been used in reference to trade guilds (c.1300). Meaning "subdivision of an infantry regiment" is from 1580s. Abbreviation co. dates from 1670s.
comparable (adj.): early 15c., from Middle French comparable, from Latin comparabilis "capable of comparison," from comparare (see comparison). Related: Comparably; comparability.
comparation (n.): late 15c., from Latin comparationem "a putting together," hence, "a comparing," noun of action from comparare (see comparison).
comparative (adj.): mid-15c., from Middle French comparatif, from Latin comparativus "pertaining to comparison," from comparat-, past participle stem of comparare (see comparison). Originally grammatical; general sense is from c.1600; meaning "involving different branches of a subject" is from 1670s. Related: Comparatively.
comparator (n.): 1883, agent noun in Latin form from compare.
compare (v.): late 14c., from Old French comparer (12c., Modern French comparer), from Late Latin comparare "to liken, to compare" (see comparison). Related: Compared; comparing. To compare notes is from 1708. Phrase without compare (attested from 1620s, but similar phrasing dates to 1530s) seems to be altered by folk etymology from compeer "rival."
comparison (n.): mid-14c., from Old French comparaison (12c.), from Latin comparationem (nominative comparatio), noun of action from past participle stem of comparare "make equal with, liken, bring together for a contest," literally "to couple together, to form in pairs," from com- "with" (see com-) + parare "prepare" (see pare).
compartment (n.): 1560s, from Middle French compartiment "part partitioned off" (16c.), through Italian compartimento, from Late Latin compartiri "to divide," from com-, intensive prefix (see com-), + partis, genitive of pars "part" (see part (n.)).
compartmental (adj.): 1831, from compartment + -al (1).
compartmentalization (n.): 1923, from compartmentalize + -ation.
compartmentalize (v.): 1918, from compartmental + -ize. Related: Compartmentalized; compartmentalizing.
compass (n.): c.1300, "space, area, extent, circumference," from Old French compas "circle, radius, pair of compasses" (12c.), from compasser "to go around, measure, divide equally," from Vulgar Latin *compassare "to pace out" (source of Italian compassare, Spanish compasar), from Latin com- "together" (see com-) + passus "a step" (see pace (n.)).

The mathematical instrument so called from mid-14c. The mariners' directional tool (so called since early 15c.) took the name, perhaps, because it's round and has a point like the mathematical instrument. The word is in most European languages, with a mathematical sense in Romance, a nautical sense in Germanic, and both in English.
compass (v.): c.1300, "to devise, plan;" early 14c. as "to surround, contain, envelop, enclose;" from Anglo-French cumpasser, from compass (n.). Related: Compassed; compassing.
compassion (n.): mid-14c., from Old French compassion "sympathy, pity" (12c.), from Late Latin compassionem (nominative compassio) "sympathy," noun of state from past participle stem of compati "to feel pity," from com- "together" (see com-) + pati "to suffer" (see passion).

Latin compassio is an ecclesiastical loan-translation of Greek sympatheia (see sympathy). An Old English loan-translation of compassion was efenðrowung.
compassionate (adj.): 1580s, from compassion + -ate (1). Related: Compassionately. Phrase compassionate conservatism in American political language recorded by 1992, popularized, if not coined, by Marvin Olasky, University of Texas at Austin instructor.
compatible (adj.): mid-15c., from Middle French compatible (15c.), from Medieval Latin compatibilis, from Late Latin compati (see compassion). Related: Compatibility.
compatriot (n.): 1610s, from French compatriote (16c.), from Latin compatriota, from com- "with" (see com-) + patriota "countryman" (see patriot).
comped (adj.): "given or admitted free," 1960s, see comp.
compeer (n.): early 15c., from Middle French comper, from com- "with" (see com-) + Latin parem "equal" (see par).
compel (v.): mid-14c., from Old French compellir, from Latin compellere "to drive together, drive to one place" (of cattle), "to force or compel" (of persons), from com- "together" (see com-) + pellere "to drive" (see pulse (n.1)). Related: Compelled; compelling.
compelling (adj.): c.1600, present participle adjective from compel. Meaning "irresistible" is from 1901. Related: Compellingly.
compendious (adj.): "concise," late 14c., from Old French compendieux, from Latin compendiosus "advantageous, abridged, brief," from compendium (see compendium).
compendium (n.): 1580s, from Latin compendium "a shortening, saving," literally "that which is weighed together," from compendere "to weigh together," from com- "together" (see com-) + pendere "to weigh" (see pendant). Borrowed earlier as compendi (mid-15c.).
compensable (adj.): 1660s, from French compensable (16c.), from compenser, from Latin compensare (see compensate).
compensate (v.): 1640s, "to be equivalent;" 1650s, "to counterbalance, make up for," from Latin compensatus, past participle of compensare "to weigh one thing (against another)," thus, "to counterbalance," from com- "with" (see com-) + pensare, frequentative of pendere "to weigh" (see pendant). Meaning "to recompense, remunerate" is from 1814. Related: Compensated; compensating.
compensation (n.): late 14c., "action of compensating," from Latin compensationem (nominative compensatio) "a weighing one thing against another, a balancing," noun of action from past participle stem of compensare (see compensate). Meaning "what is given in recompense" is from c.1600; meaning "amends for loss or damages" is from 1804; meaning "salary, wages" is attested from 1787, American English. The psychological sense is from 1914.
compensatory (adj.): c.1600, from French compensatoire, from Latin compensatus, past participle of compensare (see compensate). Psychological sense is from 1921.
compere (n.): 1738, from French compère "a godfather," from Old French compere (13c., from Medieval Latin compater) "godfather," also a friendly greeting, "friend, brother," hence "fellow, familiar, intimate" (see compadre).
compete (v.): 1610s, " to enter or be put in rivalry with," from Middle French compéter "be in rivalry with" (14c.), or directly from Late Latin competere "strive in common," in classical Latin "to come together, agree, to be qualified," later, "strive together," from com- "together" (see com-) + petere "to strive, seek, fall upon, rush at, attack" (see petition (n.)).

Rare 17c., revived from late 18c. in sense "to strive (alongside another) for the attainment of something" and regarded early 19c. in Britain as a Scottish or American word. Market sense is from 1840s (perhaps a back-formation from competition); athletics sense attested by 1857. Related: Competed; competing.
competence (n.): 1590s, "rivalry" (based on compete); c.1600 "adequate supply;" 1630s, "sufficiency of means for living at ease," from French compétence, from Latin competentia "meeting together, agreement, symmetry," from competens, present participle of competere, especially in its earlier sense of "fall together, come together, be convenient or fitting" (see compete). Meaning "sufficiency to deal with what is at hand" is from 1790.
competency (n.): 1590s, "rivalry;" c.1600, "sufficiency to satisfy the wants of life," from Latin competentia "meeting together, agreement, symmetry," from competens, present participle of competere (see compete). Meaning "sufficiency of qualification" is recorded from 1797.
competent (adj.): late 14c., "suitable," from Old French competent "sufficient, appropriate, suitable," from Latin competentem (nominative competens), present participle of competere "coincide, agree" (see compete). Meaning "able, fit" is from 1640s. Legal sense is late 15c.
competition (n.): c.1600, "action of competing," from Latin competitionem (nominative competitio) "agreement, rivalry," noun of action from past participle stem of competere (see compete). Meaning "a contest for something" is from 1610s. Sense of "rivalry in the marketplace" attested from 1793; that of "entity or entities with which one competes" is from 1961, especially in business.
competitive (adj.): 1826, from Latin competit-, past participle stem of competere (see compete) + -ive. Related: Competitively; competitiveness.
competitor (n.): 1530s, from Middle French compétiteur (16c.), or directly from Latin competitor "rival," agent noun from competere (see compete).
compilation (n.): early 15c., "that which is compiled," also "action of compiling," from Middle French compilation, from Latin compilationem (nominative compilatio) "a compilation," literally "a pillaging," noun of action from compilare (see compile).
compile (v.): early 14c., from Old French compiler "compile, collect" (13c.), from Latin compilare "to plunder, rob," probably originally "bundle together, heap up;" hence "to pack up and carry off," from com- "together" (see com-) + pilare "to compress, ram down." Related: Compiled; compiling.