ascertain

/ˌæsəˈteɪn/verb

To find something out for certain by checking or investigating.

Example sentence

“The inspector tried to ascertain the cause of the fire.”

Legal and bureaucratic in register. In conversation, "find out" says the same thing without the starch.

Related words

ashamedFeeling embarrassment or guilt about something one has done or is.ascendTo go or move upward; to rise or climb.aspirationA strong hope or longing to achieve something, especially a lofty goal.articulateAble to express thoughts clearly and effectively in words.aspireTo aim for or eagerly wish to achieve a goal.arrogantBehaving as if you are better or more important than other people, often with disdain for them.