-da
From open-dictionary.com - the free dictionary.
Finnish
Infinitive suffix
-da (with back vowel harmony)
-dä (with front vowel harmony)
- A suffix present in certain first infinitives, short form, the citation form of Finnish verbs.
Notes
When this suffix is omitted, what remains is the stem of the verb. With the verbs nähdä and tehdä, the consonant stem is left. The first consonant of the following word or enclitic is lengthened.