Pratītyasamutpāda refers to the dependant origination of phenomena. This is to say that if a series of phenomenas, or dharmas, are pratītyasamutpāda no one of them can arise independently of the other; “if this exists, that exists; if this ceases to exist, that also ceases to exist”.
In Buddhist philosophy the Twelve Nidanas are said to be pratītyasamutpāda.