From middle english "dogge", from Old English "docga". It's the male term for a canine, a female is a bitch.

This article is kind of interesting: http://www.etymonline.com/index.php?term=dog

1) "The English word dog might derive from the Old English docga, a "powerful breed of canine"." Source and further information: http://en.wikipedia.org/wiki/Dog#Etymology_and_taxonomy 2) "dog sb. Late OE. docga (once in a gloss; also g. pl. in place-names. doggeneford, doggeneberwe), of unkn. orig.; the gen. term was hund HOUND, which dog finally displaced in this status. For the formation cf. the animal-names FROG 1, PIG, STAG, *sucga in hæÄ¡sucga hedge-sparrow, *wicga beetle in EARWIG." "The Concise Oxford Dictionary of English Etymology 1996" Source and further information: http://www.encyclopedia.com/doc/1O27-dog.html 3) "Etymology is not an exact science. Dogca, according to OED and other sources wasn't the standard OE word for dog. It was applied to just one fast and powerful breed, and has one citation, meaning it was rare. Hund was the standard word, deriving from the Germanic, and before that the Indo-European languages. What's strange about dogca (becoming dogge) is that it just appears in England, late in the OE period and over the next 400 years ousts the pan-European hund. It even gets adopted in other languages (Danish dogge, and the French for mastiff, dogue). The mystery, such as it is (and as Cabs pointed out), is just that we don't know where it arrived from, or why it became so popular." "The IE [Indo-European] /swnd/ (how it was pronounced, we just have no way of knowing) has become /sag/ in Persian, /hund/ in German, and /hound/ in English. As for the phonetic relationship between /s/ and /h/, we have linguistic evidence in the Sanskrit (Indian) /asura/ 'demon' for the Persian development of the word as /ahura/ 'god' (pronounced [a.hoo.ra]), as in the Zoroastrian Ahura Mazdā 'the wise lord; i.e., God'." "The word for "dog" is, and is not, a mystery. It is linguistically possible to proof that this word is a derivative of the old IE for "horse", as in Persian asb. For the sake of argumment, let us compare the following specimens for "dog" and "horse" in different Iranian dialects: "dog": Old Iranian çván (you can see the derivative "hound" in it, don't you?), švā (which could be related to the French cheval 'horse'); Young Avestan (that is, the latter period of the two Avestan periods) spā; Old Persian * spaco-; Middle Persian sak, sag; Semnāni esbe; Tāleši sipa; Kāšghari esbá, espá; Afghani (yes, it is an Iranian dialect) spai; etc. Now let us compare these with the Iranian words for "horse": OlPers. asa-; Median aspa-; Av. aspa-; Mid. Pers. asp; New Pers. asb. As we can see, it is possible to relate these two words; especially that in Persian a diminutive suffix as Mid. Pers. [-ag], New Pers. [-ak] exists. Therefore, we may conclude that the Persian word sag 'dog' is in its earlier development * aspag, *aswag, etc. 'the little horse' (as in little horsy). All that said, this hypothesis could very well be wrong; in which case, the word for "dog" would still remain as a mystery." Source and further information: http://qi.com/talk/viewtopic.php?t=4586&postdays=0&postorder=asc&start=0 http://qi.com/talk/viewtopic.php?t=4586&postdays=0&postorder=asc&start=15