1. noun /dəˈklɑɪn/
It is also pertinent to note that the current obvious decline in work on holarctic hepatics most surely reflects a current obsession with cataloging and with nomenclature of the organisms—as divorced from their study as living entities.
2. verb /dəˈklɑɪn/
The dollar has declined rapidly since 2001.
b) To become weaker or worse.
My health declined in winter.
Wikipedia foundation.