ostensibly

Near-synonyms: reportedly, reputedly, purportedly, putatively, rumoredly, supposedly, allegedly, possibly, probably, likely, plausibly, presumably; see also Thesaurus:ostensibly

Her interest in his welfare was ostensibly charitable and magnanimous, but people began wondering who was going to inherit his assets when he died.

On 13 June the peshwa signed a new treaty, ostensibly complying with the demands of the British government[…]

1889, Leslie Stephen, Sidney Lee, Dictionary of National Biography

Up to a year or two ago it had been the custom to kill horses in the yards — ostensibly for fertilizer; […]

1905 April–October, Upton Sinclair, chapter IX, in The Jungle, New York, N.Y.: Doubleday, Page & Company, published 26 February 1906, →OCLC

The original branch was 5¾ miles long, from Llantrisant to Cowbridge only, but in 1889, the T.V.R. [Taff Vale Railway] obtained powers […] to continue the line for 6½ miles south to the coast at Aberthaw, ostensibly for the purpose of serving the important limestone works there, but one suspects other motives, including an understandable desire on the part of the T.V.R. to put a spoke in the wheel of the oncoming Barry Railway !

1951 December, T. B. Sands, “Some Railway Byways in the Vale of Glamorgan”, in Railway Magazine, page 838