What is the meaning of -ul?

Form of -il after the vowels O / U and a consonant other than L.

Added to a word to form an intransitive verb with a middle-voice meaning.

as, with the intention of

Added to an adjective to form an adverb.

alternative form of -el (“agentive suffix”)

alternative form of -el

alternative form of -ol

variant of -l

Form of -il after the vowels O / U and a consonant other than L.

Source: wiktionary.org