-ty 1
a suffix of numerals denoting multiples of ten: twenty; thirty.
[ ME; OE -tig; c. OFris -tich, G -zig, ON -tigr, Goth -tigjus ]
-ty 2
a suffix occurring in nouns of Latin origin, denoting quality, state, etc.: unity; enmity.
[ ME -te ( e ) -te ( t ) -tatem, acc. of -tas ]