呎 was coined in the late Qing as a single-character unit symbol —
口 (mouth/marker) +
尺 (chǐ, the traditional Chinese foot, ~33.3 cm). It is read chǐ but specifically denotes the imperial foot of 0.3048 m, distinguishing it from the native
尺. Mainland Chinese now writes this as
英尺 ("English chǐ");
呎 survives in older texts, in Hong Kong and Taiwan, and on architectural plans.
