dis- and un-

Prefix of "un" and "not"

Un- and dis- mean “not.” Look at unlock. Unlock means “to not lock.” When the prefix un- is added to lock, it changes the meaning of the word.

The prefix un- has been in the language longer than dis-.

The Old English prefix on- (now spelled un-) was added to verbs to indicated a reversal of the action: eg:  wind/unwind, fold/unfold, do/undo.  It also gives us verb opposites such as: cover/uncover, wrap/unwrap.

Dis- came into English during the Middle English period, along with many Latin and French words. The prefix dis- is related to bis, (two), and can be used in the sense of separation, eg: disjoin, disable

In the course of centuries, distinctions between un- and dis- have blurred. Sometimes you can use either prefix, but other times you can't. Both the prefixes have the similar meaning of "not".

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