Ostensible
Etymology
From Medieval Latin "ostensibilis," "that may be shown," from Latin "ostendere" ("to show, display"), itself from "ob-" ("toward") plus "tendere" ("to stretch"). The word began meaning simply "presentable" or "capable of being shown." Because what is shown may differ from what is hidden, it drifted to its modern sense — outwardly declared, but perhaps a front.
adjective · /oh-STEN-suh-bul/
Stated or appearing to be the reason or purpose, but possibly not the real one.
What it names
A quiet flag of doubt: use it when you want to report someone’s professed motive while signalling that the true one may lie underneath.
Example
The ostensible purpose of the trip was research, though everyone knew he mostly wanted the beach.
Related idea
Near putative, but they differ: putative means commonly supposed or reputed to be true, while ostensible hints that the appearance is a deliberate surface.