opadati

1. (of amount, level) to decline; to decrease; to fall
   Broj stanovnika na selu stalno opada. — The number of people in the village keeps declining.
   Temperatura polako opada posle ponoći. — The temperature slowly drops after midnight.
2. (of leaves, hair) to fall off; to fall out
   U oktobru lišće opada sa drveća. — In October the leaves fall from the trees.
   Od stresa mi opada kosa. — My hair is falling out from stress.

Intransitive: "cene opadaju" (prices are falling); it takes no object.