insufficient

/ɪnsəˈfɪʃɪnt/

/ɪnsəˈfɪʃənt/

If something is insufficient, it isn't enough. A high school diploma is very helpful for getting a job, but by itself, it's probably insufficient to land you a job as an astronaut.

Something adequate is sufficient, and something inadequate is insufficient (in- meaning "not"). If you have $100 in the bank and you try to use a debit card for a $102 purchase, even though you’re close to having enough, your funds are insufficient to cover the sale. Anything that falls short of a required amount or expected measure is insufficient, whether it's the amount of air in a bike tire or the votes needed to win an election.

Definitions of insufficient

1. adjective

   of a quantity not able to fulfill a need or requirement
   “insufficient funds”

   synonyms: deficient

   meager, meagerly, meagre, scrimpy, stingy

   deficient in amount or quality or extent

   depleted, low

   no longer sufficient

   inadequate, poor, short

   not sufficient to meet a need

   lean, skimpy

   containing little excess

   light, scant, short

   less than the correct or legal or full amount often deliberately so

   shy

   short

   antonyms:

   sufficient

   of a quantity that can fulfill a need or requirement but without being abundant

   ample

   more than enough in size or scope or capacity

   adequate, decent, enough

   sufficient for the purpose

   comfortable

   sufficient to provide comfort