in·con·stant
adjective/ɪnˈkɒnstənt/
/ɪnˈkɑːnstənt/
(formal)- not faithful in love or friendship
（对爱情或友情）不忠的，不专一的 - that frequently changes
不稳定的；经常变换的
Word Originlate Middle English: via Old French from Latin inconstant-, from in- ‘not’ + constant- ‘standing firm’ (from the verb constare, from con- ‘with’ + stare ‘stand’).