Definition from Wiktionary, the free dictionary
Alternative forms 
Old English meaning "full of".
- Used to form adjectives from nouns. An adjective derived by this suffix implies a thorough and certain possession of the quality of that noun, not a metaphorical fullness with it by degree or quantity. One who is wakeful is fully awake, not frequently waking; what is changeful is uncertain, not transformed; what is harmful may do a single and a mild injury.
- Used to form nouns from nouns meaning “as much as can be held by what is denoted by the noun”
Derived terms 
having the quality of the noun
Old English 
- full of