TROP-

I. combining form

or tropo-

Etymology: International Scientific Vocabulary, from Greek, from tropos — more at trope

1. : turn : turning : change

tropo meter

tropo sphere

2. : affinity for : tendency to turn toward : tropism

trop ic

tropo taxis

II. combining form

also tropa-

Etymology: International Scientific Vocabulary, from tropine

1. : tropine

trop ate

tropa cocaine

2. : atropine

trop oyl