D defs.my
Entry 2 senses Webster, 1913

opportunistic

· IPA /ˌɑ.pɚˌt(j)uːˈnɪs.tɪk/
01 adj. taking immediate advantage, often unethically, of any circumstance of possible benefit; practising opportunism.
  1. 1.
    taking immediate advantage, often unethically, of any circumstance of possible benefit; practising opportunism.
  2. 2.
    Causing disease only when the immune system of the host has been weakened, or other damage to the host provides special opportunity for invasion; -- of microorganisms or infectious diseases; as, opportunistic pathogens may infect a burn site; AIDS predisposes a patient to opportunistic infection.(Med.)