食 (shí) — (bound form) food; meal; (bound form) to eat (archaic, in set phrases or compounds)

食 (shí) is a bound form used inside set compounds — common in 食物, 食堂, 饮食 — and almost never stands alone in modern Chinese.

Two or more meaningful parts placed together so that their meanings combine into a new one.

The form behind 食 shows 亼, a mouth, together with 皀, a bowl of rice on a stand. In modern 食, the bowl part has changed shape.