word-forming element meaning "art, craft, skill," later "technical, technology," from Latinized form of Greek tekhno-, combining form of tekhnē "art, skill, craft in work; method, system, an art, a system or method of making or doing," from PIE *teks-na- "craft" (of weaving or fabricating), from suffixed form of root *teks- "to weave," also "to fabricate."
word-forming element meaning "billion" (U.S.) in the metric system, 1947, formed arbitrarily from Greek gigas "giant" (see giant).
word-forming element meaning "one thousand," introduced in French 1795, when the metric system was officially adopted there; irregularly reduced from Greek khilioi "thousand," from PIE *gheslo- "thousand," source also of Sanskrit sahasra-, Avestan hazanjra "thousand." "It is usually assumed that Lat. mille should be connected too" [Beekes]; see milli-. "In the metric system, kilo- means multiplied, & milli- divided, by 1000" [Fowler].
in the metric system, word-forming element denoting one-tenth of the standard unit of measure, 1801, from French deci-, taken arbitrarily from Latin decimus "tenth," from decem "ten" (from PIE root *dekm- "ten").
word-forming element used in making names for very small units of measure, 1915 (formally adopted as a scientific prefix meaning "one trillionth" by the International System of Units, 1960), from Spanish pico "a little over, a small balance," literally "sharp point, beak," a word of Celtic origin (compare Gaulish beccus "beak").