Online Etymology Dictionary

log (n.): late 14c., of unknown origin. O.N. had lag "felled tree" (from stem of liggja "to lie"), but on phonological grounds etymologists deny that this is the root of English log. Instead, they suggest an independent formation meant to "express the notion of something massive by a word of appropriate sound." Logging "act of cutting timber" is from 1706. Logjam "congestion of logs on a river" is from 1885; in the figurative sense it is from 1890. Log cabin in Amer.Eng. has been a figure of the honest pioneer since the 1840 presidential campaign of William Henry Harrison.
log (v.): "to enter into a log book," 1823, from logbook "daily record of a ship's speed, progress, etc." (1679), which is so called because wooden floats were used to measure a ship's speed. To log in in the computing sense is attested from 1963.
loganberry: 1893, Amer.Eng., named for U.S. horticulturalist James H. Logan (1841-1928), who developed it by crossing a blackberry and a raspberry.
logarithm: 1610s, Mod.L. logarithmus, coined by Scot. mathematician John Napier (1550-1617), lit. "ratio-number," from Gk. logos "proportion, ratio, word" (see logos) + arithmos "number" (see arithmetic). Related: Logarithmic.
logger: 1734, from log (n.).
loggerhead: 1588, "stupid person, blockhead," from dial. logger "heavy block of wood." Later it meant "a thick-headed iron tool" (1687), a type of cannon shot, a type of turtle (1657). Loggerheads "fighting, fisticuffs" is from 1680, but the exact notion is uncertain, perhaps it suggests the heavy tools used as weapons. The phrase at loggerheads "in disagreement" is first recorded 1831.
loggia: "roofed galley used as an open-air room," 1782, from It., from Fr. loge (see lodge (n.)).
logic: mid-14c., "branch of philosophy that treats of forms of thinking," from O.Fr. logique, from L. (ars) logica, from Gk. logike (techne) "reasoning (art)," from fem. of logikos "pertaining to speaking or reasoning," from logos "reason, idea, word" (see logos). Meaning "logical argumentation" is from c.1600.
logical: early 16c., "pertaining to logic," from logic + -al. Attested from 1580s as "conformable to laws of reasoning;" 1860 as "following as a reasonable consequence." Related: Logically.
logician: late 14c., from Fr. logicien (see logic).
login: in computer sense, as one word, by 1983, from log (v.) + in.
logistic: "pertaining to logic," 1628, from M.L. logisticus, from Gk. logistikos "pertaining to logic," from logikos (see logic).
logistics: "art of moving, quartering, and supplying troops," 1879, from Fr. (l'art) logistique "(art) of quartering troops," from M.Fr. logis "lodging," from O.Fr. logeis "shelter for an army, encampment," from loge (see lodge) + Gk. suffix -istikos.
logo: 1937, probably a shortening of logogram "sign or character representing a word" (1840), from Gk. logos "word" + gram "what is written."
logon: in computer sense, as one word, by 1975, from log (v.) + in.
logorrhea: 1902, from logos + ending from diarrhea.
logos: 1580s, "second person of the Christian Trinity," from Gk. logos "word, speech, discourse," also "reason," from PIE base *leg- "to collect" (with derivatives meaning "to speak," on notion of "to pick out words;" see lecture); used by Neo-Platonists in various metaphysical and theological senses and picked up by N.T. writers. Other Eng. formations from logos include logolatry "worship of words, unreasonable regard for words or verbal truth" (1810 in Coleridge); logomachy "fighting about words" (1560s); logomania (1870); logophobia (1923).
logrolling: in the legislative vote-trading sense, 1823, Amer.Eng., from the notion of neighbors on the frontier helping one another with the heavy work of clearing land and building cabins (as in phrase you roll my log and I'll roll yours); see log (n.) + roll (v.).
logy: "dull and heavy," 1848, Amer.Eng., perhaps from Du. log "heavy, dull."
-logue: suffix meaning "one who is immersed in or driven by," mostly from Fr.-derived words, from Gk. -logos, -logon, but now mostly superseded by -loger, -logist except in ideologue and a few others.
-logy: "a speaking, discourse, treatise, doctrine, theory, science," from Gk. -logia (often via Fr. -logie or M.L. -logia), from root of legein "to speak;" thus, "the character or department of one who speaks or treats of (a certain subject);" see lecture.
-ology: suffix indicating "branch of knowledge, science," the usual form of -logy, with the -o- belonging to the preceding element.
allogenic: 1961, modern coinage, parallel to Gk. allogenes "of another race, stranger," from allo-, comb. form of allos "other, different" + genos "kind, race."
anaesthesiologist: 1947, from anaesthesia + -ologist.
analog: U.S. spelling of analogue (q.v.).
analogous: 1640s, from L. analogus, from Gk. analogos "according to due proportion" (see analogy).
analogue: 1826, "an analogous thing," from Fr. analogue, from Gk. analogon (itself used in Eng. from c.1810), from ana "up to" + logos "account, ratio" (see lecture). Computing sense is recorded from 1946.
analogy: 1540s, from L. analogia, from Gk. analogia "proportion," from ana- "upon, according to" + logos "ratio," also "word, speech, reckoning." A mathematical term used in a wider sense by Plato.
anesthesiologist: alt. spelling of anaesthesiologist (q.v.). See ae.
anesthesiology: alt. spelling of anaesthesiology (q.v.). See ae.
anthology: 1630s, from L. anthologia, from Gk. anthologia "flower-gathering," from anthos "a flower" (see anther) + logia "collection, collecting," from legein "gather" (see lecture). Modern sense (which emerged in Late Gk.) is metaphoric, "flowers" of verse, small poems by various writers gathered together.
anthropology: "science of the natural history of man," 1590s, coined from Gk. anthropo- + -logia "study of." In Aristotle, anthropologos is used literally, as "speaking of man." Related: Anthropological (1825); anthropologist (1798).
apologetic: 1640s, "vindicatory," from Fr. apologétique, from L. apologeticus, from Gk. apologetikos "defensible," from apologeisthai (see apology). Meaning "regrefully acknowledging failure" is from 1855. Related: Apologetics (c.1753).
apologise: British spelling of apologize (see apology); for suffix, see -ize.
apologist: 1630s, from Fr. apologiste, from Gk. apologia "defense" (see apology).
apologize: 1590s, "to speak in defense of," from Gk. apologeisthai (see apology). Main modern sense "to regretfully acknowledge" is attested by 1725. The Gk. equivalent, apologizesthai, meant simply "to give an account."
apologue: "moral fable," 1550s, from Fr. apologue, from L. apologus, from Gk. apologos, from apo- "off, away from" + logos "speech" (see lecture). Lit. "(that which comes) from a speech."
apology: 1530s, "defense, justification," from L.L. apologia, from Gk. apologia "a speech in defense," from apologeisthai "to speak in one's defense," from apologos "an account, story," from apo- "from, off" (see apo-) + logos "speech." The original English sense of "self-justification" yielded a meaning "frank expression of regret for wrong done," first recorded 1590s, but it was not the main sense until 18c. The old sense tends to emerge in Latin form apologia (first attested 1784), especially since J.H. Newman's "Apologia pro Vita Sua" (1864).
archaeology: c.1600, "ancient history," from Fr. archéologie, from Gk. arkhaiologia "the study of ancient things," from arkhaios "ancient," from arkhe "beginning" (see archon). Meaning "scientific study of ancient peoples" first recorded 1837. Related: Archaeologist (1824).
archeological: alt. spelling of archaeological (q.v.). Also see ae.
archeologist: alt. spelling of archaeologist (q.v.). Also see ae.
archeology: alt. spelling of archaeology (q.v.). Also see ae.
astrologer: late 14c., from astrology (q.v.). Drove out Fr. import astrologein, which, had it survived, probably would have yielded *astrologian; cf. Chaucer's "The wise Astrologen."
astrology: late 14c., from L. astrologia "astronomy," from Gk. astrologia "telling of the stars," from astron "star" (see astro-) + -logia "treating of," comb. form of logon "one who speaks (in a certain manner)." Originally identical with astronomy, it had also a special sense of "practical astronomy, astronomy applied to prediction of events." This was divided into natural astrology "the calculation and foretelling of natural phenomenon" (tides, eclipses, etc.), and judicial astrology "the art of judging occult influences of stars on human affairs" (also known as stromancy, 1650s). Differentiation between astrology and astronomy began late 1400s and by 17c. this word was limited to "reading influences of the stars and their effects on human destiny." Astrological is recorded from 1590s.
audiology: science of hearing and treatment of deafness, coined 1947, from audio- + -ology. Related: Audiologist.
backlog: 1680s, from back + log. Originally a large log placed at the back of a fire. Figurative sense is first attested 1883, via notion of "a reserve of something stored up."
bacteriology: 1884, from Ger.; see bacteria.
battology: c.1600, "needless repetition in speaking or writing," from Gk. battologia "a speaking stammeringly," from battos "stammerer," of imitative origin, + -logia, from -logos "one who speaks (in a certain manner)."
biological: 1859, from biology + -ical. Biological clock attested from 1955; not especially of human reproductive urges until c.1991.
biologist: 1813, from biology + -ist.