The word xiā cāi literally combines 瞎 (xiā), meaning 'blind' or 'without sight', and 猜 (cāi), meaning 'to guess' or 'to speculate'. Together, they form an idiomatic verb meaning 'to guess blindly' — that is, to make a guess without any evidence, logic, or basis, often carelessly or randomly. It carries a slightly negative or humorous connotation, suggesting the guess is unlikely to be correct and may even be foolish or irresponsible.

This expression is commonly used in informal spoken and written Chinese, especially when commenting on someone’s unfounded assumptions — for instance, in discussions about exams, mysteries, rumors, or technical problems. While it can be self-deprecating ('I’m just瞎猜'), it’s more frequently used to gently tease or point out the lack of reasoning behind another person’s speculation. It does not imply malice, but rather highlights the absence of supporting information.