pleni-comb. form

Stress is usually determined by a subsequent element and vowels may be reduced accordingly; see e.g. 
plenisphere n.Origin: A borrowing from Latin. Etymon: Latin plēni-.
Etymology:  <  classical Latin plēni- (in e.g. plēnilūniuim  plenilunium n.), combining form of plēnus   full (see full adj.); compare -i- connective.First attested in Middle English in Latin loans, as plenilune n., plenitude n.   Formations within English are found from the first half of the 17th cent. (see e.g. pleni-tide n.).
This is a new entry (OED Third Edition, September 2006; most recently modified version published online March 2020).