any of a group of organic substances essential in small quantities to normal metabolism
"After noticing my fatigue, I decided to take a multivitamin supplement to ensure I was getting enough of these essential organic substances for proper metabolic function."
Any of a specific group of organic compounds essential in small quantities for healthy human growth, metabolism, development, and body function; found in minute amounts in plant and animal foods or sometimes produced synthetically; deficiencies of specific vitamins produce specific disorders.
"The doctor prescribed a daily multivitamin supplement to help the child recover from his severe deficiency after months of poor eating habits."
In plain English: A vitamin is a tiny nutrient your body needs to stay healthy but cannot make on its own, so you must get it from food.
"Taking a daily vitamin helps keep my immune system strong."
Usage: Use the singular form when referring to one type of nutrient or taking supplements individually. The plural is required only when discussing multiple distinct vitamins within your diet.
Coined in 1912 by Polish scientist Casimir Funk from the Latin word for "life" and a suffix meaning "amine," the term originally suggested these essential nutrients were all amines. Although scientists later discovered that some vitamins, like vitamin C, contain no amine at all, British biochemist Jack Drummond dropped the final "-e" in 1920 to remove this misleading implication while keeping the word's connection to life intact.