Tolerance is the ability of the body to adapt to a drug.
Tolerance has been observed to develop to many, but not all, of the effects of marijuana in adult animals. A tremendous degree of tolerance to marijuana is observed, but there is an absence of withdrawal symptoms. Szeto HH, Wu DL, Decena JA, Cheng Y. Effects of single and repeated marijuana smoke exposure on fetal eeg. Maternal marijuana smoking alters respiratory timing in the fetal lamb. Neurobiology of marijuana abuse.