null and void

null and void idiom
Canceled, invalid, as in The lease is now null and void. This phrase is actually redundant, since null means “void,” that is, “ineffective.” It was first recorded in 1669.

The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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