Many words have an obvious antonym, such as near and far or over and under.
However, there are quite a lot of words that have more than one antonym. Sometimes this is because the same word can mean different things.
right (meaning 'correct') and wrong
right (as in 'right hand side') and left
Sometimes there can be more than one antonym for a word with a single meaning. The antonym of open can be either shut or closed.