The term 'fixate upon' can be summarized as 'STARE intently'. It is a phrase used to describe someone who is focused on something or someone with great intensity. This phrase is often used to describe someone who is so focused on something that they are unable to take their eyes off of it. The crossword solution for this phrase is 'STARE', which is a verb meaning to look at something or someone for a long period of time without blinking.