c. 1600, "to select by lot and put to death every tenth man," from Latin decimatus, past participle of decimare "the removal or destruction of one-tenth," from decem "ten" (from PIE root *dekm- "ten").
The killing of one in ten, chosen by lots, from a rebellious city or a mutinous army was a punishment sometimes used by the Romans. The word has been used (loosely and unetymologically, to the irritation of pedants) since 1660s for "destroy a large but indefinite number of." Related: Decimated; decimating.
mid-15c., decimacioun, "the paying of tithes, a tithing, a tax of 10% on income," from Old French decimacion and directly from Late Latin decimationem (nominative decimatio) "the taking of a tenth," noun of action from past-participle stem of Latin decimare "the removal or destruction of one-tenth," from decem "ten" (from PIE root *dekm- "ten").
As "punishment by capital execution of every tenth man, chosen by lot," from 1580s; loose or transferred sense of "destruction of a great but indefinite number, severe loss" is attested by 1680s.
1520s, "find out, discover" (a sense now obsolete); 1540s, "interpret (a coded writing, etc.) by the use of a key," from de- + cipher (v.). Perhaps in part a loan-translation from French déchiffrer. From c. 1600 in the transferred sense of "discover or explain the meaning of what is difficult to understand." Sense of "succeed in reading what is written in obscure or partially obliterated characters" is by 1710. Related: Deciphered; deciphering.
mid-15c., "act of deciding," from Old French décision (14c.), from Latin decisionem (nominative decisio) "a decision, settlement, agreement," noun of action from past-participle stem of decidere "to decide, determine," literally "to cut off," from de "off" (see de-) + caedere "to cut" (from PIE root *kae-id- "to strike").
Meaning "final judgment or opinion in a case" is from 1550s. Meaning "quality of being decided in character, ability to make prompt determinations" is from 1781; sense of "a resolution, a fixing of purpose" is by 1886. Decision-making (adjective) is recorded by 1946.
mid-15c., dekke, "covering extending from side to side over part of a ship," from a nautical use of Middle Dutch dec, decke "roof, covering," from Proto-Germanic *thakam (source also of thatch (n.)), from PIE root *(s)teg- "to cover."
Sense extended early in English from "covering" to "platform of a ship." Meaning "pack of cards necessary to play a game" is from 1590s, perhaps because they were stacked like decks of a ship. Tape-deck (1949) is in reference to the flat surface of old reel-to-reel tape recorders.
Deck-chair (1844) so called because they were used on ocean liners. On deck (by 1740) was in nautical use especially "ready for action or duty;" extended sense in baseball, of a batter waiting a turn at the plate, is by 1867. To clear the deck (1852) is to prepare a ship for action; it is perhaps a translation of French débarasser le pont.
"adorn, array or clothe with something ornamental" (as in deck the halls), early 15c., from Middle Dutch decken "to cover, put under roof," a nautical word, from Proto-Germanic *thakjan (source also of Old Frisian thekka, Old High German decchan, German decken), from PIE root *(s)teg- "to cover." Meaning "to cover, overspread" is from 1510s in English. Replaced Middle English thecchen, from Old English eccan(see thatch (v.), which is a doublet).Related: Decked; decking.