Old English weddung "state of being wed" (see wed). Meaning "ceremony of marriage" is recorded from c.1300; the usual Old English word for the ceremony was bridelope, literally "bridal run," in reference to conducting the bride to her new home. Wedding cake is recorded from 1640s; as a style of architecture, attested from 1879.
Old English weddian "to pledge, covenant to do something, marry," from Proto-Germanic *wadjojanan (cf. Old Norse veðja "to bet, wager," Old Frisian weddia "to promise," Gothic ga-wadjon "to betroth"), from PIE root *wadh- "to pledge, to redeem a pledge" (cf. Latin vas, genitive vadis "bail, security," Lithuanian vaduoti "to redeem a pledge"). Sense remained "pledge" in other Germanic languages (cf. German Wette "bet, wager"); development to "marry" is unique to English. "Originally 'make a woman one's wife by giving a pledge or earnest money', then used of either party" [Buck]. Related: Wedded; wedding.