disallow

[dis-uh-lou]
verb (used with object)
  1. to refuse to allow; reject; veto: to disallow a claim for compensation.
  2. to refuse to admit the truth or validity of: to disallow the veracity of a report.

Origin of disallow

First recorded in 1350–1400; Middle English word from Old French word desallouer. See dis-1, allow
Related formsdis·al·low·a·ble, adjectivedis·al·low·a·ble·ness, noundis·al·low·ance, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for disallowable

disallow

verb (tr)
  1. to reject as untrue or invalid
  2. to cancel
Derived Formsdisallowable, adjectivedisallowance, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for disallowable
adj.

mid-15c., from disallow + -able.

disallow

v.

late 14c., "to refuse to praise," from Old French desalouer "to blame," from des- (see dis-) + alouer (see allow); meaning "to reject" is from 1550s. Related: Disallowed; disallowing; disallowance.

Online Etymology Dictionary, © 2010 Douglas Harper