pirouette (n.)

diminutive word-forming element, from Old French -ette (fem.), used indiscriminately in Old French with masculine form -et (see -et).

As a general rule, older words borrowed from French have -et in English, while ones taken in since 17c. have -ette.

In use with native words since late 19c., especially among persons who coin new product names, who tend to give it a sense of "imitation, a sort of" (for example flannelette "imitation flannel of cotton," 1876; leatherette, 1855; linenette, 1894). It also formed such words as lecturette (1867), sermonette, which, OED remarks, "can scarcely be said to be in good use, though often met with in newspapers." A small supermarket in U.S. sometimes was a superette (1938), an etymological impossibility.