(number theory) A number that is less than the sum of its proper divisors (all divisors except the number itself).

(mathematics) A number that can be expressed as the ratio of two integers.

(grammar) A noun that is morphologically related to a verb and similar to it in meaning; in English, it contrasts with the gerund and the deverbal noun.

(food, broadly) Any of various hard-shelled seeds or hard, dry fruits from various families of plants. / (botany, strictly) Such a fruit that is indehiscent.

(mostly in the form "nutting") To gather nuts. / (UK, transitive, slang) To hit deliberately with the head; to headbutt. / (slang, mildly vulgar) To orgasm; to ejaculate.

(Scotland, colloquial) No.

A mark or token by which a thing may be known; a visible sign; a character; a distinctive mark or feature; a characteristic quality.

(transitive) To notice with care; to observe; to remark; to heed. / (transitive) To record in writing; to make a memorandum of. / (transitive) To denote; to designate. / (transitive) To annotate.

(uncountable, UK dialectal, Northern England, Ireland, Scotland) That which is needed or necessary; business; duty; work.

Used in the sense of no or none, to show lack of or failure to perform; or in the sense of not, to negate the meaning of the word to which it is prefixed.