cramyoudaoicibaDictYouDict[cram 词源字典]
cram: [OE] Prehistoric Germanic had a base *kram-, *krem- which denoted ‘compression’ or ‘bending’. Among its descendants were Old Norse kremja ‘squeeze, pinch’, German krumm ‘crooked’ (source of English crumhorn [17], a curved Renaissance musical instrument), and Old English crammian (ancestor of cram), which meant ‘press something into something else, stuff’.

An extension of the base with p (*kramp-, *kremp-) produced Middle Low German and Middle Dutch krampe ‘bent’, one or other of which was borrowed by Old French as crampe and passed on to English as cramp [14] (crampon [15] comes from a related source). Other products of the Germanic base were Old English crumb ‘crooked’, a possible ancestor of crumpet, and perhaps crimp [17].

A nonnasalized version of the base produced Germanic *krappon ‘hook’, source of grape and grapnel.
=> crampon, crimp, crumhorn, crumpet, grape, grapnel[cram etymology, cram origin, 英语词源]
cram (v.)youdaoicibaDictYouDict
Old English crammian "press something into something else," from Proto-Germanic *kram-/*krem- (cognates: Old High German krimman "to press, pinch," Old Norse kremja "to squeeze, pinch"), from PIE root *ger- "to gather" (see gregarious). Meaning "study intensely for an exam" originally was British student slang first recorded 1803. Related: Crammed; cramming.