/ ɒˈstensəbl; NAmE ɑːˈst-/ adjective
[ only before noun ] seeming or stated to be real or true, when this is perhaps not the case
SYN apparent :
The ostensible reason for his absence was illness.
► os·ten·sibly / -əbli; NAmE / adverb :
Troops were sent in, ostensibly to protect the civilian population.
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WORD ORIGIN
mid 18th cent.: from French , from medieval Latin ostensibilis from Latin ostens- stretched out to view, from the verb ostendere , from ob- in view of + tendere to stretch.