abbreviation for glutamic acid, an amino acid; also informal for glue
shortened form of 'glutamic acid' from Latin 'gluten' meaning 'glue'
GLU is biochemistry shorthand for glutamic acid, one of the building blocks of proteins! It's funny that both 'glue' and 'glutamic acid' come from the same Latin root - they're both about sticking things together, just at very different scales.
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