mid-14c., "keep back or in store for future use;" late 14c., "keep as one's own," from Old French reserver "set aside, withhold" (12c.) and directly from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect"). Meaning "to book" is from 1935. Related: Reserved; reserving.
1610s, "something stored up," from reserve (v.) or from French réserve, a back-formation from reserver "set aside, withhold," from Latin reservare "keep back, save up; retain, preserve," from re- "back" (see re-) + servare "to keep, save, preserve, protect" (from PIE root *ser- (1) "to protect").
Meaning "self-imposed restraint on freedom of words or actions; habit of keeping back the feelings" is from 1650s. The meaning "district or place set apart for some particular use" is by 1805. The sense of "amount of capital kept on hand to meet probable expenses or demand" is by 1866. That of "amount of natural resources known to exist in a particular region" is by 1912. As an adjective, "kept in reserve," by 1719.
The military sense of "body of troops withheld from action to serve as reinforcements, etc." is from 1640s; that of "national emergency defense or auxiliary military force" (reserves) is by 1866.
1670s, "a bottom, the bottom; foundation, groundwork," from French fond "a bottom, floor, ground" (12c.), also "a merchant's basic stock or capital," from Latin fundus "bottom, foundation, piece of land" (from PIE root *bhudh- "bottom, base," source also of Sanskrit budhnah, Greek pythmen "foundation, bottom," Old English botm "lowest part;" see bottom (n.)). Meaning "stock of money or wealth available for some purpose" is from 1690s; sense of "store of anything to be drawn upon" is from 1704. Funds "money at one's disposal" is from 1728.
1776, "convert (a debt) into capital or stock represented by interest-bearing bonds," from fund (n.). Meaning "supply (someone or something) with money, to finance" is from 1900.
1540s, from Latin subsidiarius "belonging to a reserve, of a reserve, reserved; serving to assist or supplement," from subsidium "a help, aid, relief, troops in reserve" (see subsidy). As a noun, c. 1600, "subsidiary thing." In Latin the word was used as a noun meaning "the reserve."
by 1948, acronym from United Nations International Children's Emergency Fund, which was created in 1946 (the name was changed 1953 to United Nations Children's Fund but the acronym endured).