Finnish word itku comes from Finnish itkeä ((intransitive) To cry, weep.), Finnish -u

Detailed word origin of itku

Dictionary entry	Language	Definition
itkeä	Finnish (fin)	(intransitive) To cry, weep.
-u	Finnish (fin)	Derives a number of nouns from other nouns.. Forms nouns from verbs. Most common with e- and i-stem verbs.
itku	Finnish (fin)	Cry (shedding of tears).

Words with the same origin as itku