unlaughable

As a noun terms

is .

As an adjective unlaughable is

not laughable; at which one cannot or should not laugh.

As a noun laugh

is an expression of mirth particular to the human species; the sound heard in laughing; laughter.

As a verb laugh

is to show mirth, satisfaction, or derision, by peculiar movement of the muscles of the face, particularly of the mouth, causing a lighting up of the face and eyes, and usually accompanied by the emission of explosive or chuckling sounds from the chest and throat; to indulge in laughter.

As an adjective unlaughable is

not laughable; at which one cannot or should not laugh.

As adjectives the difference between laughable and unlaughable

is that laughable is worthless; worthy of contempt or derision while unlaughable is not laughable; at which one cannot or should not laugh.