-ty
-ty (1)
suffix representing "ten" in cardinal numbers that are multiples of 10 (sixty, seventy, etc.), from Old English -tig, from a Germanic root (cognates: Old Saxon, Dutch -tig, Old Frisian -tich, Old Norse -tigr, Old High German -zug, German -zig) that existed as a distinct word in Gothic (tigjus) and Old Norse (tigir) meaning "tens, decades."
-ty (2)
suffix used in forming abstract nouns from adjectives (such as safety, surety), Middle English -tie, -te, from Old French -te (Modern French -té), from Latin -tatem (nominative -tas, genitive -tatis), cognate with Greek -tes, Sanskrit -tati-.
early 14c., savete, "freedom or immunity from harm or danger; an unharmed or uninjured state or condition," from Old French sauvete, salvete "safety, safeguard; salvation; security, surety," earlier salvetet (11c., Modern French sauveté), from Medieval Latin salvitatem (nominative salvitas) "safety," from Latin salvus "uninjured, in good health, safe" (from PIE root *sol- "whole, well-kept").
