1) to make known one's thoughts, to declare
2) to say
Part of Speech: verb
Properly the same as the base of G5457 and G5316; to show or make known one's thoughts, that is, speak or say: - affirm, say. Compare G3004.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root φημί; click on the second column to search for that grammatical form of the root φημί; click on the third column to search for that word and grammatical form; click on the total to search for the root φημί.