Definition of -eer suffix from the Oxford Advanced Learner's Dictionary

  1. 1(in nouns) a person concerned with auctioneer mountaineer
  2. 2(in verbs) (often disapproving) to be concerned with profiteer commandeer
  3. Word Originfrom French -ier, from Latin -arius; verbs are often back-formations (e.g. electioneer from electioneering).
See the Oxford Advanced American Dictionary entry: -eer