supplement

noun

• 1something that completes or enhances something else when added to it:the handout is a supplement to the official manual
• a substance taken to remedy the deficiencies in a person’s diet:multivitamin supplements
• a separate section, especially a color magazine, added to a newspaper or periodical.

• 2 Geometry the amount by which an angle is less than 180°.

verb

• add an extra element or amount to:she took the job to supplement her husband’s income