ino·sin·ic acid \| ̷ ̷ ̷ ̷|sinik-\noun Etymology: part translation of German inosinsäure, from inosin inosine + säure acid : an amorphous nucleotide C10H13N4O8P that is found in muscle and is formed by deamination of adenylic acid and that yields hypoxanthine, ribose, and phosphoric acid on hydrolysis