disloyalty

UK: /ˌdɪsˈlɔɪəlti/ US: (dis loi′əl tē)

Inflections of 'disloyalty' (n): npl: disloyalties

WordReference Random House Unabridged Dictionary of American English © 2025

dis•loy•al•ty  (dis loi′əl tē), n., pl. -ties. 

1. the quality of being disloyal;
   lack of loyalty;
   unfaithfulness.
2. violation of allegiance or duty, as to a government.
3. a disloyal act.

• Middle French desloiaute, Old French desleaute, equivalent. to desleal disloyal + -te -ty²
• late Middle English 1400–50

Synonyms

• 1. faithlessness, subversion.
  Disloyalty, perfidy, treachery, treason imply betrayal of trust.
  Disloyalty applies to any violation of loyalty, whether to a person, a cause, or one's country, and whether in thought or in deeds:
  to suspect disloyalty in a friend.
  Perfidy implies deliberate breaking of faith or of one's pledges and promises, on which others are relying:
  It is an act of perfidy to cheat innocent people.
  Treachery implies being secretly traitorous but seeming friendly and loyal:
  In treachery deceit is added to disloyalty.
  Treason is performing overt acts to help the enemies of one's country or government:
  Acting to aid a hostile power is treason.

Collins Concise English Dictionary © HarperCollins Publishers::

disloyalty / dɪsˈlɔɪəltɪ/ noun ( -ties)

1. the condition or an instance of being unfaithful or disloyal

WordReference Random House Learner's Dictionary of American English © 2025

dis•loy•al /dɪsˈlɔɪəl/   adj. 

1. false to one's allegiances;
   faithless:
   He was disloyal to his own department by snitching to the boss.

dis•loy•al•ty, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

dis•loy•al  (dis loi′əl), adj. 

1. false to one's obligations or allegiances;
   not loyal;
   faithless;
   treacherous.

• Middle French desloial, Old French desleal, equivalent. to des- dis-¹ + leal loyal
• 1470–80

dis•loy′al•ist, n. 
dis•loy′al•ly, adv. 
Synonyms

unfaithful, perfidious, traitorous, treasonable.