Adverbial overtime has 1 sense
  1. overtime - beyond the regular time; "she often has to work overtime"
,Noun overtime has 2 senses
  1. overtime - work done in addition to regular working hours
    --1 is a kind of
    work time
  2. overtime, extra time - playing time beyond regulation, to break a tie
    --2 is a kind of time period, period of time, period
    --2 is a part of athletic game
    Antonyms: regulation time
    --2 has particulars: extra innings; overtime period; tiebreaker; sudden death