musty

Short definition from Wiktionary

Adjective

1. 1
   Affected by dampness or mould; damp, mildewed, mouldy.
2. 2
   Having an odour or taste of mould; also (generally), having a stale or unfresh odour or taste.
3. 3
   Characteristic of or relating to mould or mouldiness.
4. 4
   Of attitudes, ideas, writing, or other abstract things: no longer fresh or interesting; outdated, stale.
5. 5
   Of a person: boring and unadventurous; also, old-fashioned, stuck in the past.
6. 6
   Bad-tempered, grumpy, irritable.
7. 7
   Of a male animal such as a camel or an elephant: in musth.

Noun

1. 1
   A type of snuff with a musty flavour (adjective sense 2).

Verb

1. 1
   To turn musty (adjective sense 1 or 2); to must.