- -ful [fəl; ] for 2, usually [ fool][ME < OE < full, FULL1] suffix1. forming adjectivesa) full of, characterized by, having [joyful, painful]b) having the qualities of [masterful]c) having the ability or tendency to, apt to [helpful, forgetful]2. forming nouns the quantity that fills or would fill: the plural is formed by adding -s to the resulting word [teaspoonfuls, handfuls] or, sometimes, by adding -s- between the noun stem and the suffix [cupsful]
English World dictionary. V. Neufeldt. 2014.