Eight n. : An island in a river; an ait.

Eight a. : Seven and one; as, eight years.

Eight n. : The number greater by a unit than seven; eight units or objects.

Eight n. : A symbol representing eight units, as 8 or viii.

Example:
Can an Eight week old mosquitofish be pregnant?

Taxonomy
number 8, glyph, holy number, free encyclopedia, BCE, the Eight, eighth day, duration, wealth, Eights, song, suit, babies, lucky number, sports, games, aliquot sum, Fibonacci number.

Defination from the web:
eight in Wiktionary, the free dictionary. 8 (eight) is the natural number following 7 and preceding 9. The SI prefix for 10008 ... In the beginning, various groups in India wrote eight more or less in one stroke as a curve that looks like an uppercase H with the bottom half ...