蓋

Phono-semantic compound (形聲 /形声, OC *kaːbs, *kaːb, *ɡaːb): semantic 艸 (“grass”) + phonetic 盍 (OC *ɡaːb) — a thatch.

盍 is the original character for the “cover” sense. However, because this original character was borrowed to mean “why not”, the scope of senses for 蓋 expanded to include the “cover” sense (and its extended meanings).

From Proto-Sino-Tibetan *(g/k)wap (“to cover, incubate, hatch”). Within Chinese, compare:

* 盍 (OC *ɡaːb, “to join, unite; door leaf”)

* 閤 (OC *kuːb, “small gate”)

* 蛤 (OC *kuːb, “oyster, mussel”)

* 合 (OC *kuːb, *ɡuːb, “to join, unite; harmony; to close, shut”)

* 洽 (OC *ɡruːb, “to unite, assemble; to accord with”)

* 翕 (OC *qʰrub, “united, harmonious”)

Outside of Sinitic, cognate with Mizo [Term?] (hûap, “to include, to take in, to cover, to embrace, to apply to”). The Sino-Tibetan root is likely allofamic with Proto-Tibeto-Burman *ʔup (“idem”), the latter whence Burmese အုပ် (up, “to cover”) (STEDT).