Etymology
Advertisement
cog (n.)

c. 1300, "wheel having teeth or cogs;" late 14c., "tooth on a wheel," probably a borrowing from a Scandinavian language (compare Norwegian kugg "cog") and cognate with Middle High German kugel "ball."

Related entries & more 
Advertisement
cog-wheel (n.)

"wheel having teeth or cogs," early 15c., from cog (n.) + wheel (n.).

Related entries & more 
kugel (n.)
kind of pudding in Jewish cookery, 1846, from Yiddish kugel, literally "ball," from Middle High German kugel "ball, globe" (see cog (n.)).
Related entries & more 
cam (n.1)

1777, "a projecting part of a rotating machinery used to impart motion to another part," from Dutch cam "cog of a wheel," originally "comb," from Proto-Germanic *kambaz "comb," from PIE root *gembh- "tooth, nail." It is thus a cognate of English comb (n.). This might have combined with English camber "having a slight arch;" or the whole thing could be from camber. It converts regular rotary motion into irregular, fast-and-slow rotary or reciprocal motion. "The original method was by cogs or teeth fixed or cut at certain points in the circumference or disc of a wheel ..." [OED]. Cam-shaft attested from 1850.

Related entries & more 
cognize (v.)

"perceive, become conscious of," 1650s, back-formation from cognizance. The French word is connaître (Old French conoistre). Related: Cognized; cognizing.

Related entries & more 
Advertisement
cognition (n.)

mid-15c., cognicioun, "ability to comprehend, mental act or process of knowing," from Latin cognitionem (nominative cognitio) "a getting to know, acquaintance, knowledge," noun of action from past participle stem of cognoscere "to get to know, recognize," from assimilated form of com"together" (see co-) + gnoscere "to know" (from PIE root *gno- "to know"). In 17c. the meaning was extended to include perception and sensation.

Related entries & more 
cogitate (v.)

"to think earnestly or seriously," 1560s (transitive); 1630s (intransitive); from Latin cogitatus, past participle of cogitare "to think" (see cogitation). Related: Cogitated; cogitating.

Related entries & more 
cognizable (adj.)

1670s, "capable of being known," also "liable to be tried in a given court or jurisdiction," from stem of cognizance (q.v.) + -able. Related: Cognizably; cognizability.

Related entries & more 
cogent (adj.)

"compelling assent or conviction," 1650s, from French cogent "necessary, urgent" (14c.), from Latin cogentem (nominative cogens), present participle of cogere "to curdle; to compel; to collect," literally "to drive together," from assimilated form of com "together" (see co-) + agere "to set in motion, drive, drive forward; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move"). Related: Cogently.

Related entries & more