Consisting of a single element or component

• Of one kind, in chemistry
• Having but one component
• Having one component
• Having a single part
• Having a single element
• Having only one component
• Having a single component
• Consisting of a single element
• Taking a single operand, in math

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1923, from Latin unus "one" (see one ) on model of binary , etc.