1. Lack of knowledge or mental capacity; idiocy; foolishness 
2. An idiom; a form, mode of expression, or signification, peculiar to a language

Derived forms: idiotisms

• decagonal
• decagram
• decahedron
• decal
• decalcification
• decalcify
• decalcomania
• decalescence
• decalescent
• decaliter
• decalitre
• Decalogue
• decameter
• decametre
• decamp
• decampment
• decanal
• decane
• decanedioic acid
• decani
• decanoic acid
• decant
• decantation
• decanter
• decapitate