Etymology: Cognate with Old High German rato (Middle High German rat , rate ), weak masculine, and Middle Dutch ratte , rotte (Dutch rat , rot ), Old Saxon ratta (Middle Low German rotte ; > Old Swedish rotta (Swedish råtta )), Old High German ratte (Middle High German rate , ratte , German Ratte ), weak feminine, of uncertain origin (see below). Compare post-classical Latin ratus , rattus rat (from 12th cent. in British and continental sources; also raturus (first half of the 11th cent.: see quot. OE at sense 1a)), Anglo-Norman and Old French rat , masculine (second half of the 12th cent.; Middle French, French rat ), Old French rate , feminine (second half of the 12th cent.; also Middle French, French rate female rat (1530)), Old Occitan rata (12th cent.), rat (13th cent.; probably in sense ‘mouse’), Catalan rata , rat (both 13th cent.), Spanish rata (1250; also rato mouse (1250)), Portuguese rato (14th cent.), Italian †ratto (a1400). Compare also ratton n.It is uncertain whether the Latin and Romance words are cognate with the Germanic words, or whether they were borrowed from Germanic, or vice versa; in any case the ultimate origin is uncertain; perhaps imitative of the sound of gnawing. None of the Latin and Romance words is attested before the end of the first millennium, and the fact that the German word has not undergone the High German sound shift suggests that the Germanic group is also late (Middle High German ratz , ratze , German regional (chiefly southern) Ratz , Ratze are secondary, perhaps hypocoristic formations). The word was probably spread with the reintroduction of rats to Northern Europe during the Viking Age (for a discussion of the physical evidence compare P. L. Armitage in Antiquity 68 (1994) 231–40). A derivation < an ablaut variant of the Indo-European base of classical Latin rōdere to gnaw (see rodent adj.) has been suggested, but seems unlikely in the light of the apparently recent introduction of the word. A suggested derivation of the Romance words < classical Latin rapidus rapid adj. is no longer accepted, as it would only account for the Italian, which for chronological and historical reasons cannot be the single origin of the whole group. With the forms rotte , rott compare Dutch and Middle Low German forms with -o- (which were also borrowed into the Scandinavian languages; compare rottan n.). Apparently attested early as a byname and surname: Aluinus ret (1086), Osbertus Rate (1086; perhaps reflecting an unattested Old English weak form: compare the continental Germanic forms cited above), Jordan Rat (a1189), Walterus le Rat (1189–99), Rob. Rat (1203–4), etc., although it is unclear whether the later examples are to be interpreted as reflecting the Middle English or the Anglo-Norman word. Compare the unambiguously English diminutive formation in the surname of John Ratekin (1251). Also attested in place names (and surnames derived from them), as Rettescroft (1225 in the name of Nicholas de Rettescroft ; now Rushcroft Farm, Surrey), Rattesbourgh (1303; now Ratsborough, Essex); compare also Rettendun (11th cent.; now Rettendon, Essex), perhaps implying the existence of an unattested Old English adjective *rætten . Compare also the earlier partially translated place name: pontium de Rat (1185), although, once again, it is unclear whether this is to be interpreted as reflecting the Middle English or the Anglo-Norman word. With rat of Inde n. at sense 2 compare Middle French, French †rat d'Inde (1562); compare later Indian rat n. at Indian adj. and n. Compounds 1a(b). With rat of Suriname n. compare French †rat de Surinam (1771); compare also Suriname rat n. at Suriname n. Compounds 1a. In sense 8 after rat v.⁵ 1.