imitating

Could someone please tell me what the prefix, base word, and suffix would be of above word?

From the Online Etymology Dictionary:

http://www.etymonline.com/index.php?term=imitation

Since "imitate" is related to "imago" in Latin, there is no prefix. The suffix on this word is clearly -ing. So the base of this word must be "imitat" from the Latin and Old French.