disorientate

From dis- +‎ orientate.^[1] Not a back-formation from disorientation, which is attested much later and is perhaps from disorientate.^[2]

disorientate (third-person singular simple present disorientates, present participle disorientating, simple past and past participle disorientated)

1. (sometimes proscribed, chiefly British) Alternative form of disorient
   • 1941, Frederic William Eggleston, Search for a Social Philosophy, page 254:

     Ideas often disorientate a system which has been formed on a particular pattern and make it inapplicable; so ideas may lead to the readjustment of groups and sometimes of political boundaries.

• disorientation

• “orient, orientate, disorient”, in Writing Tips Plus (Canada.ca), Ottawa, Ont.: Government of Canada, 2020 February 28: “The verbs orient and orientate are both acceptable, with orient being more common in North America. […] The antonym for both verbs is disorient; disorientate is non–standard English.”
• Paul Brians (2009) “orientate”, in Common Errors in English Usage, 2nd edition, Wilsonville, Or.: William, James & Company, →ISBN: “Although it is standard in British English ‘orientate’ is widely considered an error in the US, with simple ‘orient’ being preferred. The same pattern applies to ‘disorientate’ vs. ‘disorient.’”

disorientate

1. inflection of disorientare:
   1. second-person plural present indicative
   2. second-person plural imperative

disorientate f pl

1. feminine plural of disorientato