Online Etymology Dictionary

reflection (n.): late 14c., reflexion, in reference to surfaces throwing back light or heat, from Late Latin reflexionem (nominative reflexio) "a reflection," literally "a bending back," noun of action from past participle stem of Latin reflectere "to bend back, bend backwards, turn away," from re- "back" (see re-) + flectere "to bend" (see flexible). Of the mind, from 1670s. Meaning "remark made after turning back one's thought on some subject" is from 1640s. Spelling with -ct- recorded from late 14c., established 18c., by influence of the verb.
reflex (n.): c. 1500, "reflection of light," from verb reflex meaning "refract, deflect" (late 14c.), from Late Latin reflexus "a bending back," noun use of past participle of reflectere (see reflection). Meaning "involuntary nerve stimulation" first recorded 1877, from reflex action (1833).
reflect (v.): late 14c., "turn or bend back;" early 15c., "to divert, to turn aside, deflect," from Old French reflecter (14c.), from Latin reflectere "bend back, turn back" (see reflection). Of mirrors or polished surfaces, to shine back light rays or images, early 15c.; meaning "to turn one's thoughts back on" is c. 1600. Related: Reflected; reflecting.
advisement (n.): early 14c., avisement "examination, inspection, observation," from Old French avisement "consideration, reflection," from aviser (see advise). Meaning "advice, counsel" is from c. 1400, as is that of "consultation, conference."
eidolon (n.): 1801, "a shade, a specter," from Greek eidolon "appearance, reflection in water or a mirror," later "mental image, apparition, phantom," also "material image, statue, image of a god, idol," from eidos "form, shape" (see -oid). By 1881 in English as "a likeness, an image."
image (n.): c. 1200, "piece of statuary; artificial representation that looks like a person or thing," from Old French image "image, likeness; figure, drawing, portrait; reflection; statue," earlier imagene (11c.), from Latin imaginem (nominative imago) "copy, imitation, likeness; statue, picture," also "phantom, ghost, apparition," figuratively "idea, appearance," from stem of imitari "to copy, imitate" (see imitation).
To þe ymage of god he made hym [Gen. i:27, Wycliffite Bible, early version, 1382]
Meaning "reflection in a mirror" is early 14c. The mental sense was in Latin, and appears in English late 14c. Sense of "public impression" is attested in isolated cases from 1908 but not in common use until its rise in the jargon of advertising and public relations, c. 1958.
echo (n.): mid-14c., "sound repeated by reflection," from Latin echo, from Greek echo, personified in classical mythology as a mountain nymph who pined away for love of Narcissus until nothing was left of her but her voice, from or related to ekhe "sound," ekhein "to resound," from PIE *wagh-io-, extended form of root *(s)wagh- "to resound" (cognates: Sanskrit vagnuh "sound," Latin vagire "to cry," Old English swogan "to resound"). Related: Echoes. Echo chamber attested from 1937.
Minerva: ancient Roman goddess of arts, crafts, and sciences; wisdom, sense, and reflection (later identified with Greek Athene), late 14c., mynerfe, from Latin Minerva, from Old Latin Menerva, from *menes-wa, from PIE root *men- "mind, understanding, reason" (see mind (n.)). Compare Sanskrit Manasvini, name of the mother of the Moon, manasvin "full of mind or sense." Related: Minerval.
moonraker (n.): in England, a name traditionally given to Wiltshire people, attested from 1787, is from the stock joke about fools who mistook the reflection of the moon in a pond for a cheese and tried to rake it out. But as told in Wiltshire, the men were surprised trying to rake up kegs of smuggled brandy, and put off the revenuers by acting foolish.
skit (n.): "piece of light satire or caricature," 1820, from earlier sense "a satirical remark or reflection" (1727), originally (1570s) "a vain, frivolous, or wanton girl" (originally Scottish, now archaic), related to verb meaning "to shy or be skittish, caper, frolic" (1610s), perhaps from Old Norse skjuta "to shoot, move quickly" (see skittish).
consideration (n.): mid-14c., "a beholding, looking at," also "keeping in mind," from Old French consideracion (12c., Modern French considération), from Latin considerationem (nominative consideratio) "consideration, contemplation, reflection," noun of action from past participle stem of considerare (see consider). Meaning "a taking into account" is from mid-15c.; that of "something given in payment" is from c. 1600.
cogitation (n.): c. 1200, "thought, idea, notion," from Old French cogitacion "thought, consideration, reflection," from Latin cogitationem (nominative cogitatio), noun of action from past participle stem of cogitare "to think, reflect, consider, turn over in the mind," apparently from co-agitare, from com- "together" (see co-) + agitare, here in a sense of "to turn over in the mind," literally "to put in constant motion, drive, impel," frequentative of agere "to move, drive" (see agitation).
reverberation (n.): late 14c., "reflection of light or heat," from Old French reverberacion "great flash of light; intense quality," from Medieval Latin reverberationem (nominative reverberatio), noun of action from past participle stem of Latin reverberare "beat back, strike back, repel, cause to rebound," from re- "back" (see re-) + verberare "to strike, to beat," from verber "whip, lash, rod," related to verbena "leaves and branches of laurel," from PIE *werb- "to turn, bend" (see warp (v.)). Sense of "an echo" is attested from 1620s.
remembrance (n.): c. 1300, "a memory, recollection," from Old French remembrance (11c.), from remembrer (see remember). From late 14c. as "consideration, reflection; present consciousness of a past event; store of personal experiences available to recollection, capacity to recall the past." Also late 14c. as "memento, keepsake, souvenir," and "a commemoration, remembering, ritual of commemoration." Meaning "faculty of memory, capability of remembering" is early 15c.

British Remembrance Day, the Sunday nearest Nov. 11 (originally in memory of the dead of World War I) is attested from 1921. A remembrancer (early 15c.) was a royal official of the Exchequer tasked with recording and collecting debts due to the Crown; hence also, figuratively "Death" (late 15c.).
thanks (n.): Old English þanc, þonc in late use "grateful thought, gratitude," plural form thanks from mid-13c., from the same root as thank (v.). Compare Old Saxon thank, Old Frisian thank, Old Norse þökk, Dutch dank, German Dank. The Old English noun originally and chiefly meant "thought, reflection, sentiment; mind, will, purpose;" also "grace, mercy, pardon; pleasure, satisfaction."

As short for I give you thanks from 1580s; often with extensions, such as thanks a lot (1908). Spelling thanx attested by 1907.
narcissism (n.): 1905, from German Narzissismus, coined 1899 (in "Die sexuellen Perversitäten"), by German psychiatrist Paul Näcke (1851-1913), on a comparison suggested 1898 by Havelock Ellis, from Greek Narkissos, name of a beautiful youth in mythology (Ovid, "Metamorphoses," iii.370) who fell in love with his own reflection in a spring and was turned to the flower narcissus (q.v.). Coleridge used the word in a letter from 1822.
But already Krishna, enamoured of himself, had resolved to experience lust for his own self; he manifested his own Nature in the cow-herd girls and enjoyed them." [Karapatri, "Lingopasana-rahasya," Siddhanta, II, 1941-2]
Sometimes erroneously as narcism.
solemn (adj.): mid-14c., "performed with due religious ceremony or reverence, sacred, devoted to religious observances," also, of a vow, etc., "made under religious sanction, binding," from Old French solempne (12c., Modern French solennel) and directly from Latin sollemnis "annual, established, religiously fixed, formal, ceremonial, traditional," perhaps related to sollus "whole" (see safe (adj.)).

"The explanation that Latin sollemnis was formed from sollus whole + annus year is not considered valid" [Barnhart], but some assimilation via folk-etymology is possible. In Middle English also "famous, important; imposing, grand," hence Chaucer's friar, a ful solempne man. Meaning "marked by seriousness or earnestness" is from late 14c.; sense of "fitted to inspire devout reflection" is from c. 1400. Related: Solemnly.
meditation (n.): c. 1200, "contemplation; devout preoccupation; devotions, prayer," from Old French meditacion "thought, reflection, study," and directly from Latin meditationem (nominative meditatio) "a thinking over, meditation," noun of action from past participle stem of meditari "to meditate, think over, reflect, consider," frequentative form from PIE root *med- "to measure, limit, consider, advise, take appropriate measures" (cognates: Greek medesthai "think about," medon "ruler;" Latin modus "measure, manner," modestus "moderate," modernus "modern," mederi "to heal," medicus "physician;" Sanskrit midiur "I judge, estimate;" Welsh meddwl "mind, thinking;" Gothic miton, Old English metan "to measure;" also see medical).

Meaning "discourse on a subject" is early 14c.; meaning "act of meditating, continuous calm thought upon some subject" is from late 14c. The Latin verb also had stronger senses: "plan, devise, practice, rehearse, study."
cockatrice (n.): late 14c., from Old French cocatriz, altered (by influence of coq) from Late Latin *calcatrix, from Latin calcare "to tread" (from calx (1) "heel;" see calcaneous), as translation of Greek ikhneumon, literally "tracker, tracer."

In classical writings, an Egyptian animal of some sort, the mortal enemy of the crocodile, which it tracks down and kills. This vague sense became hopelessly confused in the Christian West, and in England the word ended up applied to the equivalent of the basilisk. A serpent hatched from a cock's egg, it was fabled to kill by its glance and could be slain only by tricking it into seeing its own reflection. Belief in them persisted even among the educated because the word was used in the KJV several times to translate a Hebrew word for "serpent." In heraldry, a beast half cock, half serpent.