Another word for top priority is primary.
Other words for top priority besides primary include.
Key.
Central.
Capital.
Prime.
Main.
Leading.
Highest.
Primary.
These words that are other words for top priority are synonyms of top priority.
A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language.
For example, in the English language, the words begin, start, commence, and initiate are also all synonyms of one another: they are synonymous.
Antonyms are words that have the opposite meaning of the word, like hot and cold big and small or day and night, which serve to contrast ideas and add nuance in language.
They can also be nouns, verbs, adjectives or even adverbs and understanding them also helps expand your vocabulary and clarify communication.
Common examples include up/down, fast/slow, happy/sad and love/hate.