Quisuous (adj) (Scottish) (rare)
Difficult to deal with or settle; perplexing; (of a person) of dubious character.
Late 17th century. Origin uncertain; perhaps from classical Latin quisquis whoever, with subsequent alteration of the ending after adjectives in -ous. With the form quisquose perhaps compare -ose.
“I’ve tried to explain to him but you know how quisquous he can be!”