The correct spelling of the word "ANTITI" is actually "antithy" (/ˌæntiˈθaɪ/). The word is formed by combining the prefix "anti-" and the root "thy". The "th" sound is represented by the "th" digraph, and the "y" at the end represents the suffix "-y" which forms an adjective indicating a relationship. Therefore, "antithy" means "opposing or against the thyroid gland". It is important to use the correct spelling in order to accurately communicate the meaning of the word in medical contexts.