Octopus
present tense
athletics bans clothes binoculars dress jeans glass gas lens mathematics measles mumps pants physics pincers tights tongs trousers tweezers
Technically it ends with ' only. No S. But in Strunk and White's "Elements of Style" (a very prestigious and well-followed writing guide) they suggest putting the 's in, if only for an easier read....
nouns ending in -ies = species / series nouns that end in -s = crossroads / barracks / headquarters / means / Swiss