What is the root word of "unforgivable"? [closed]

The root is forgive (From Old English forgiefan : for + giefan)

Unforgivable:

1549s from un (not) + forgivable.

Forgivable:

forgive +able

(Etymonline)


OED:

Forgive (v.) Etymology: Old English forgiefan ( < for- prefix[1] + giefan : see give v.)

The sense of "for" is quite difficult to understand as it has a variety of effects upon its verb: in this case, it is probably

b. With the sense of prohibition, exclusion, or warding off, as in forbid n. Also with the sense of concealing from view: