Of food: solid, hard to digest.

Incapable of being digested, or difficult to digest; not easily assimilated as food.

= indigestible, adj.

(un-, prefix1 affix 1.)

Uncooked, raw, crude; hence, undigested or indigestible.

Incapable of being changed into anything else; †spec. incapable of being assimilated, indigestible (cf. convertible, adj. 5b).

Indigestible.

Difficult of digestion; causing dyspepsia; indigestible. Obsolete. rare.