os ‧ ten ‧ si ‧ ble /ɒˈstensəb ə l, ɒˈstensɪb ə l $ ɑː-/ BrE AmE adjective
[ Date: 1700-1800 ; Language: French ; Origin: Latin ostendere 'to show' ]
seeming to be the reason for or the purpose of something, but usually hiding the real reason or purpose
ostensible reason/purpose/aim
The ostensible reason for his resignation was ill health.