a pp. of forbid.

not allowed; prohibited

a forbidden food in his religion.

Physics . involving a change in quantum numbers that is not permitted by the selection rules

forbidden transition.

adjective

allowed , approved , authorized , permitted , sanctioned

adjective

banned , closed , closed-down , closed-up , contraband , no-no , off limits , out of bounds , proscribed , refused , taboo * , verboten , vetoed , impermissible , taboo , denied , illicit , inhibited , inhibitory , interdicted , prohibited , tabu , tref , ultra vires , unlawful