Etymology 1

From merged meanings of Old English weak verb dyfan and strong verb dufan

Verb

1. To swim under water.
2. To jump into water head-first.
3. To descend sharply or steeply.
4. (especially with in) To undertake with enthusiasm.

   She dove right in and started making improvements.

5. To deliberately fall down after a challenge, imitating being fouled, in the hope of getting one's opponent penalised
6. To cause to descend, dunk

Usage notes

The past tense dove is found chiefly in North American English, where it is used alongside the regular (and earlier) dived, with regional variations; in British English dived is the standard past tense, dove existing only in some dialects. As a past participle, dove is relatively rare. (Cf. Merriam-Webster Collegiate Dictionary; The American Heritage Dictionary; The Cambridge Guide to English Usage)

Noun

1. A jump or plunge into water.
2. A swim under water.
3. A decline.
4. A seedy bar, nightclub, etc.
5. Fast descend with the nose of a craft pointed down.
6. A deliberate fall after a challenge.