so has the oed.
Inflections: Plural mongooses , ( irregular ) mongeese , ( irregular ) mongoose , ( irregular ) mongooze .
first mention is from 1673
1673 G. Aungier Let. 29 Sept. in C. Fawcett Eng. Factories in India (1936) I. 83 [My house is] miserably afflicted with rats so great that a mongoose or our cats will not meddle with them.
