What is prefix to document ?

In grammar, a prefix is a morpheme that is attached before a base word. Morphemes are the smallest meaningful units in the grammar of language. Attaching a prefix could modify a word’s meaning. An example of a prefix is ‘un-,’ meaning ‘not.’ The prefix ‘un-‘ can be attached to the base word ‘available’ to make it ‘unavailable,’ and negate the meaning of the base word.