The ordinal form of the number twenty-eight.

The person or thing in the twenty-eighth position. / One of twenty-eight equal parts of a whole.

The ordinal form of the number eighteen.

The person or thing in the eighteenth position. / One of eighteen equal parts of a whole. / (informal) A party to celebrate an eighteenth birthday.

The ordinal form of the number eighty.

to divide by eight

The person or thing in the eighth position. / One of eight equal parts of a whole. / (slang) An eighth of an ounce, or approximately 3.5 grams, of marijuana or other drugs.

The cardinal number occurring after seventeen and before nineteen, represented in Roman numerals as XVIII and in Arabic numerals as 18.

The person or thing in the eightieth position. / One of eighty equal parts of a whole.

From or evoking the 81st through 90th years of a century (chiefly the 1980s).