That old word - 'conscious'. We misuse it terribly. For instance we know when someone is 'unconscious', which should reasonably be the converse of being conscious. By that view, every animal that is aware and responding to its environment is conscious.

Another use (misuse?) of the word is to mean 'self-aware'. That one is harder to measure. But plenty of animals seem to meet that bar - if they recognize themselves in a mirror; if they can empathize with others etc.