英语词源字典 - 在线词源网站

burrow (n.)[burrow 词源字典]: "rabbit-hole, fox-hole, etc.," c. 1300, borewe, from Old English burgh "stronghold, fortress" (see borough); influenced by bergh "hill," and berwen "to defend, take refuge."[burrow etymology, burrow origin, 英语词源]
clap (n.2): "gonorrhea," 1580s, of unknown origin, perhaps from Middle English clapper "rabbit-hole," from Old French clapoire (Modern French clapier), originally "rabbit burrow" (of uncertain origin), but given a slang extension to "brothel" and also the name of a disease of some sort. In English originally also a verb, "to infect with clap." Related: Clap-doctor.