Etymology
Advertisement
sheet (n.2)

"rope that controls a sail," late 13c., shortened from Old English sceatline "sheet-line," from sceata "lower part of sail," originally "piece of cloth," from same root as sheet (n.1). Compare Old Norse skaut, Dutch schoot, German Schote "rope fastened to a sail."

This probably is the notion in phrase three sheets to the wind "drunk and disorganized," first recorded 1812 (in form three sheets in the wind), an image of a sloop-rigged sailboat whose three sheets have slipped through the blocks are lost to the wind, thus "out of control." Apparently there was an early 19c. informal drunkenness scale in use among sailors and involving one, two, and three sheets, three signifying the highest degree of inebriation; there is a two sheets in the wind from 1813.

It must not be wondered at that the poor, untutored, savage Kentuckyan got "more than two thirds drunk," that is, as the sailors term it, three sheets in the wind and the fourth shivering, before the dinner was ended. [Niles' Weekly Register, May 2, 1812]
Related entries & more 
Advertisement
assertion (n.)

early 15c., assercioun, "a declaration, confirmation" from Old French assercion (14c.) or directly from Late Latin assertionem (nominative assertio), noun of action from past-participle stem of Latin asserere/adserere "to claim, lay claim to, appropriate," from ad "to" (see ad-) + serere "join together, put in a row" (from PIE root *ser- (2) "to line up"). By "joining oneself" to a particular view, one "claimed" or "maintained" it. From mid-15c. as "an unsupported statement."

Related entries & more 
sheet (n.1)
Old English sciete (West Saxon), scete (Mercian) "cloth, covering, towel, shroud," from Proto-Germanic *skautjon-, from *skauta- "project" (source also of Old Norse skaut, Gothic skauts "seam, hem of a garment;" Dutch schoot; German Schoß "bosom, lap"), from PIE root *skeud- "to shoot, chase, throw."

Sense of "piece of paper" first recorded c. 1500; that of "any broad, flat surface" (of metal, open water, etc.) is from 1590s. Of falling rain from 1690s. Meaning "a newspaper" is first recorded 1749. Sheet lightning is attested from 1794; sheet music is from 1857. Between the sheets "in bed" (usually with sexual overtones) is attested from 1590s; to be white as a sheet is from 1751. The first element in sheet-anchor (late 15c.) appears to be a different word, of unknown origin.
Related entries & more 
balance-sheet (n.)
"statement showing the state of credits and debits in a particular business," 1812, from balance (n.) in the accounting sense + sheet (n.1).
Related entries & more 
broadsheet (n.)
also broad-sheet, 1705, "large sheet of paper printed on one side only," from broad (adj.) + sheet (n.). By 1831 as "a broadsheet newspaper."
Related entries & more 
Advertisement
tole (n.)
"ornamented and painted sheet iron," 1946, from French tôle "sheet iron," from dialectal taule "table," from Latin tabula "a flat board" (see table (n.)).
Related entries & more 
ipse dixit 
Latin, literally "he (the master) said it," translation of Greek autos epha, phrase used by disciples of Pythagoras when quoting their master. Hence, "an assertion made without proof, resting entirely on the authority of the speaker" (1590s), ipsedixitism "practice of dogmatic assertion" (1830, Bentham), etc.
Related entries & more 
asseveration (n.)

"an emphatic assertion," 1550s, from Latin asseverationem (nominative asseveratio) "vehement assertion, protestation," noun of action from past-participle stem of asseverare/adseverare "affirm, insist on," from ad "to" (see ad-) + severus "serious, grave, strict, austere," which is probably from PIE root *segh- "to have, hold," on the notion of "steadfastness, toughness."

Related entries & more 
assertiveness (n.)
"tendency toward self-assertion," 1867, short for self-assertiveness (1855); see assertive + -ness.
Related entries & more