英语词源字典 - 在线词源网站

contra-[contra- 词源字典]: word-forming element meaning "against, in opposition," from Latin adverb and preposition contra (see contra). The Latin word was used as a prefix in Late Latin. In French, it became contre- and passed into English as counter-. The Old English equivalent was wiðer (surviving in withers and widdershins), from wið "with, against."[contra- etymology, contra- origin, 英语词源]
extra-: word-forming element meaning "outside; beyond the scope of; in addition to what is usual or expected," in classical Latin recorded only in extraordinarius, but more used in Medieval Latin and modern formations; it represents Latin extra (adv.) "on the outside, without, except," the old fem. ablative singular of exterus "outward, outside," comparative of ex "out of" (see ex-).
extra-curricular (adj.): also extracurricular, 1911, from extra- + curricular. As a noun by 1957.
extra-special (adj.): 1841, from extra- + special (adj.). Originally of legislative sessions, later (1880s) of certain editions of daily newspapers.
intra-: word-forming element meaning "within, inside, on the inside," from Latin intra "on the inside, within," related to inter "between," from PIE *en-t(e)ro-, from root *en "in" (see in). Commonly opposed to extra-, but the use of intra as a prefix was rare in classical Latin.
tetra-: before vowels tetr-, word-forming element meaning "four," from Greek tetra-, combining form of tettares (Attic), tessares "the numeral four" (see four).
ultra-: word-forming element meaning "beyond" (ultraviolet) or "extremely" (ultramodern), from Latin ultra- from ultra (adv. and prep.) "beyond, on the other side, on the farther side, past, over, across," from PIE *ol-tero-, suffixed form of root *al- (1) "beyond" (see alias (adv.)). In common use from early 19c., it appears to have arisen from French political designations. As its own word, a noun meaning "extremist" of various stripes, it is first recorded 1817, from French ultra, shortening of ultra-royaliste "extreme royalist."
ultra-conservative (adj.): 1828, from ultra- + conservative (adj.).