expression, i-adjective
thought to be; seen as; apparently
Used after a noun or clause to express conjecture based on appearance or evidence; often literary or formal. The phrase attaches to the preceding element with と.
彼は犯人とおぼしい人物を目撃した。
He witnessed a person who appeared to be the culprit.
その建物は城跡とおぼしい。
That building seems to be the remains of a castle.
らしい is a more common and versatile suffix for conjecture or typicality, while と思しい is more formal and limited to 'thought to be' based on evidence.
ようだ expresses similarity or appearance in a broader range of contexts; と思しい is more specific to inferring identity or nature from clues.
Derived from the quotative particle と and the classical adjective おぼし (思し/覚し), meaning 'thought to be'. The modern form is とおぼしい.