It is not unusual for English words to have many meanings . There are some words that don´t just have a different meaning, but the opposite meaning. They are called contronyms, here is how a few of them ended up that way.

Off:  means ‘deactivated,’ as in «to turn off,» but also ‘activated,’ as in «The alarm went off.»

Weather:  can mean ‘to withstand or come safely through,’ as in “The company weathered the recession,” or it can mean ‘to be worn away’: “The rock was weathered.”

Fast:  can mean «moving rapidly,» as in «running fast,» or ‘fixed, unmoving,’ as in «holding fast.» If colors are fast they will not run. The meaning ‘firm, steadfast’ came first. The adverb took on the sense ‘strongly, vigorously,’ which evolved into ‘quickly,’ a meaning that spread to the adjective.

Screen : can mean ‘to show’ (a movie) or ‘to hide’ (an unsightly view).

Help : means ‘assist,’ unless you can’t help doing something, when it means ‘prevent.’

Continue :  usually means to persist in doing something, but as a legal term it means stop a proceeding temporarily.

Go:  means «to proceed,» but also «give out or fail,» i.e., “This car could really go until it started to go.”

Out:  can mean «visible» or «invisible.» For example, “It’s a good thing the full moon was out when the lights went out.”

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