subpotent

/sʌbˈpoʊtənt/
adjective
  1. Having less power, effectiveness, or strength than normal or required.
    • The subpotent signal caused the radio to pick up only static.
    • The subpotent vaccine failed to provide full immunity to the population.
    • Because the cleaning solution was subpotent, it didn't remove the stains.
Antonyms