The word 私事 is formed by directly combining two independent characters, each carrying its own core meaning. The first character, 私, represents the concept of "private" or "personal", denoting something belonging to the individual sphere. The second character, 事, signifies "matter", "affair", or "business". When placed together, they fuse conceptually: the first element "private" modifies and defines the scope of the second element "matter", resulting in the compound idea of "private matters" or "personal affairs". It is a straightforward semantic union where the whole meaning is essentially the sum of its constituent parts.