Etymology
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sink (v.)
Old English sincan (intransitive) "become submerged, go under, subside" (past tense sanc, past participle suncen), from Proto-Germanic *senkwan (source also of Old Saxon sinkan, Old Norse sökkva, Middle Dutch sinken, Dutch zinken, Old High German sinkan, German sinken, Gothic sigqan), from PIE root *sengw- "to sink."

The transitive use (mid-13c.) supplanted Middle English sench (compare drink/drench) which died out 14c. Related: Sank; sunk; sinking. Sinking fund is from 1724. Adjective phrase sink or swim is from 1660s. To sink without a trace is World War I military jargon, translating German spurlos versenkt.
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sink (n.)
early 15c., "cesspool, pit for reception of wastewater or sewage," from sink (v.). Figurative sense of "place where corruption and vice abound" is from 1520s. Meaning "drain for carrying water to a sink" is from late 15c. Sense of "shallow basin (especially in a kitchen) with a drainpipe for carrying off dirty water" first recorded 1560s. In science and technical use, "place where heat or other energy is removed from a system" (opposite of source), from 1855.
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sinker (n.)
1838 in the fishing-line sense, agent noun from sink (v.).
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sinkhole (n.)
also sink-hole, mid-15c., "sewage pit," from sink (n.) + hole (n.). As a geological phenomenon, "hole made in the earth in limestone regions by underground erosion," 1780, from sink (v.).
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sunken (adj.)
late 14c., past-participle adjective from sink (v.).
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sunk 
a past tense and past participle of sink (v.).
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unsinkable (adj.)
1650s, from un- (1) "not" + sinkable (see sink (v.)).
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thunk (v.)
dialectal or jocular past tense or past participle of think, by 1876. Not historical, but by analogy of drink/drunk, sink/sunk, etc.
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kitchen sink (n.)

sink to wash food, dishes, etc., 1824. Phrase everything but (or and) the kitchen sink is attested from 1944, from World War II armed forces slang, in reference to intense bombardment.

Out for blood, our Navy throws everything but the kitchen sink at Jap vessels, warships and transports alike. [Shell fuel advertisement, Life magazine, Jan. 24, 1944]

Earlier was everything but the kitchen stove (1919).

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