opportunistic infection
— Noun
– English
～ any infection caused by a microorganism that does not normally cause disease in humans; occurs in persons with abnormally functioning immune systems (as AIDS patients or transplant patients receiving immunosuppressive drugs)
opportunistic
— Adjective
– English
～ taking immediate advantage, often unethically, of any circumstance of possible benefit
opportunity
— Noun
– English
～ a possibility due to a favorable combination of circumstances; "the holiday gave us the opportunity to visit Washington"; "now is your chance"
opportunity cost
— Noun
– English
～ cost in terms of foregoing alternatives