a bomb that has a detonating mechanism that can be set to go off at a particular time
a problematic situation that will eventually become dangerous if not addressed; "India is a demographic time bomb"; "the refugee camp is a ticking bomb waiting to go off"
(theology) the origination of the Holy Spirit at Pentecost; "the emanation of the Holy Spirit"; "the rising of the Holy Ghost"; "the doctrine of the procession of the Holy Spirit from the Father and the Son"
something that is emitted or radiated (as a gas or an odor or a light etc.)