While true in general (all terms are just arbitrary terms humans assign to stuff!), usually there are underlying well-defined concepts that can be associated with common-sense language and common-sense notions. For example, a line is probably a very ancient notion, but it was made more well-defined in Euclidean geometry. I don't think intelligence is a meaningless concept, but I do think there are a number of different more or less well-defined underlying concepts or formal definitions. I tend to associate intelligence with ability to reach (potentially fuzzy) goals or satisfy certain conditions (time-continued goals), solve problems, etc.. Where I live I think there is some controversy around the term artificial intelligence because people associate intelligence with more broad cognitive activity maybe including consciousness.
In fact I think this is a particularly important distinction right now, that intelligence seems (to me somewhat unexpectedly/counterintuitively) somewhat independent from consciousness, at least as far as artificial systems go (for example, old school chess engines are much capable than humans at chess but are definitely not sentient or conscious).
In fact I think this is a particularly important distinction right now, that intelligence seems (to me somewhat unexpectedly/counterintuitively) somewhat independent from consciousness, at least as far as artificial systems go (for example, old school chess engines are much capable than humans at chess but are definitely not sentient or conscious).