[Adverb] When something seems to be the case but probably is not. Example: The directors put in an offer to buy the company, ostensibly to protect workers jobs.
Found on http://www.bbc.co.uk/skillswise/glossary/
Os·ten'si·bly adverb In an ostensible manner; avowedly; professedly; apparently. Walsh. « Ostensibly , we were intended to prevent filibustering into Texas, but really as a menace to Mexico.» U. S. Grant. Found on http://www.encyclo.co.uk/webster/O/38