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.
for example:
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.