"liable to fall down," 1680s, from rickets (with + -y (2)), via notion of "weak, unhealthy." Literal sense is from c. 1720 but never common in English. Of material things, from 1799.
例文
1. He followed her up a rickety staircase to a squalid bedsit.
彼は彼女についてふらふらとした階段を上り、だらしない寝室の居間両用部屋に来た。
2.Mona climbed the rickety wooden stairway.
モナはよろよろとした木の階段を登った。
3.He was precautious in crossing the rickety bridge.