Not full, large, or plentiful; scarcely sufficient; less than is wanted for the purpose; scanty; meager; not enough; as, a scant allowance of provisions or water; a scant pattern of cloth for a garment.
Not quite up to full measure. For example: a scant teaspoon of an ingredient would be less than a teaspoonful as opposed to a level teaspoon, rounded teaspoon or heaping teaspoon.