Τὸ γὰρ περισσὰ πράσσειν οὐκ ἔχει νοῦν οὐδένα → There is no sense in doing things beyond the usual measure
P. and V. ἄτοπος (Euripides, Fragment).
ridiculous: P. and V. γέλοιος, Ar. and P. καταγέλαστος.
unreasonable: P. ἄλογος.
monstrous: P. πάνδεινος; see monstrous.