zidovudine: an antiviral drug (trade name Retrovir) used in the treatment of AIDS; adverse side effects include liver damage and suppression of the bone marrow
nucleoside reverse transcriptase inhibitor: an antiviral drug used against HIV; is incorporated into the DNA of the virus and stops the building process; results in incomplete DNA that cannot create a new virus; often used in combination with other drugs
collapse: a natural event caused by something suddenly falling down or caving in