I. noun
( -s )
Etymology: from gerund of strengthen
1. : an act or instance of reinforcing
advised an immediate strengthening of the faculty — J.E.Pomfret
2. archaic : reinforcement
piers of brick or stone … to be a strengthening to the building — B.G.Gerbier
II. adjective
Etymology: from present participle of strengthen
1. : tending to strengthen
a strengthening element in the design — R.E.M.Wheeler
2. : increasing in strength or intensity
objects became clearer in the strengthening light