Race condition
A race condition or race hazard is the behavior of an electronics, software, or other system where the system's substantive behavior is dependent on the sequence or timing of other uncontrollable events. It becomes a bug when one or more of the possible behaviors is undesirable.
Lethal allele
Alleles that will only be fatal in response to some environmental factor are referred to as conditional lethals. One example of a conditional lethal is favism, a sex-linked inherited condition that causes the carrier to develop hemolytic anemia when they eat fava beans.