hollow · ​. having a hole or empty space inside · ​(of parts of the face) sinking deeply into the face. hollow eyes/cheeks · ​[usually before noun] (of sounds) ...

having a hole or empty space inside; a hollow ball/center/tube; The tree trunk was hollow inside. Her stomach felt hollow with fear.

​an area that is lower than the surface around it, especially on the ground. All but one of the ponds are empty, their sites marked only by muddy hollows.

There are five meanings listed in OED's entry for the noun hollow. See 'Meaning & use' for definitions, usage, and quotation evidence.

a hole or a small space in something The squirrel disappeared into a hollow at the base of the tree. See hollow in the Oxford Advanced Learner's Dictionary.

​to make a flat surface go inward in a curve. be hollowed (by something) The stairs have been hollowed by centuries of use.

to make a flat surface curve in The stairs have been hollowed by centuries of use. Want to learn more? Find out which words work together.

There are 13 meanings listed in OED's entry for the word hollow, one of which is labelled obsolete. See 'Meaning & use' for definitions, usage, and quotation ...

​to make a hole in something by removing part of it. Hollow out the cake and fill it with cream. a gun concealed in a hollowed-out book.

to make a hole in something by removing part of it. Hollow out the cake and fill it with cream. a gun concealed in a hollowed-out book.