verb

• (poker, bridge) To call a bet after another player has already called
  "Jill bet, Tommy called, and Julie overcalled."
• (medicine) To diagnose a condition that does not, in fact, exist.
  "Knowledge of the ultrasound findings is important, and appreciating the fetal ultrasound may often undercall or (more often) overcall anomalies."

noun

• (poker, bridge) A call which occurs after another player has already called
• (contract law) An additional contribution required of investors beyond the initial investment, should unforeseen expenses arise.
  "Respondent further asserts that the only reason the overcall provision was included in the partnership agreement was to circumvent the provisions of section 465."
• (medicine) A positive diagnosis when there is, in fact, nothing wrong.
  "According to published data, screening with chemiluminescence, as opposed to other light sources, imparts the lowest overcall rate."