Tupperware component that often loses its pair

URL ender for MIT or UCLA3 Deer on Michigan's flag3 Female deer3 ___ Hohn, athlete with a record-breaking javelin throw that sped up the introduction of a new javelin design that wouldn't allow for long throws3 "Do you want an ice cream cone ___ brownie?": 2 wds.3 Spanish "hey!"3 Inflexible, like a muscle or a rule5 Not a cathode (rhymes with "abode")5