mustiest
mus-ti-est
adjective
Having the strongest unpleasant stale, damp, or mouldy smell or taste.
"The attic had the mustiest odour."
Thesaurus
Synonyms: malodorous, ill-smelling, stinky, fusty, musty, frowsty, unpleasant-smelling, malodourous, mouldy, stale, moldy