OH With a Negative Charge
This page is the CodyCross answer for the clue below from The 80s, Group 791, Puzzle 4 (Space Exploration).
Question is: OH With a Negative Charge
and the answer is: HYDROXIDE
Word Meaning:
HYDROXIDE — (chemistry) A univalent anion (OH⁻) based on the hydroxyl functional group.
Definitions from Wiktionary.