"Dissociate" vs "disassociate"
Both "dissociate" and "disassociate" are defined as removing an association but is there a difference between the two? Does the "associate" part of "disassociate" imply a stronger former connection missing in "dissociate?"
OED says disassociate dates from 1603, and dissociate from 1623, so neither is meaningfully "the original". They're basically the same word, but if you believe this NGram dissociate is used more commonly by a factor of about 4:1 in total.
Many instances of disassociate will in any case be for the specialised chemical sense (compounds breaking down into atoms, ions, etc.) which only applies to that form, so for OP's meaning the usage figures are even more skewed.
Merriam-Webster's dictionary of English usage implies that apart from where that difference in meaning applies, you should probably prefer the shorter word - partly because it is shorter, and partly because it's the more common form. There are no other considerations, or differences in use or nuance.
While the meanings of the two words are the same, the usages do not overlap in any of the technical fields.
Chemistry - Ionization, dissociation, and dissolution: These are three related terms covering the breaking apart of chemical species. If you see disassociation in place of dissociation, consider it an error.
Dissociation
(1) The separation of a molecular entity into two or more molecular entities (or any similar separation within a polyatomic molecular entity). Examples include mimolecular heterolysis and homlysis, and the separation of the constituents of an ion pair into free ions. (2) The separation of the constituents of any aggregate of molecular entities. In both senses dissociation is the reverse of association
INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY
ORGANIC CHEMISTRY DIVISION
COMMISSION ON PHYSICAL ORGANIC CHEMISTRY
GLOSSARY OF TERMS USED IN PHYSICAL ORGANIC CHEMISTRY
https://www.iupac.org/publications/pac/pdf/1994/pdf/6605x1077.pdf
(Disassociation is not listed in this or the two other glossaries of chemistry terms that I checked.)
Psychology
Dissociative amnesia The inability to remember important personal experiences, caused by psychological factors in the absence of any organic dysfunction.
Dissociative disorder A personality disorder marked by a disturbance in the integration of identity, memory, or consciousness.
Dissociative identity disorder (DID) A dissociative mental disorder in which two or more distinct personalities exist within the same individual; formerly known as multiple personality disorder.
Found on the American Psychology Association website -
Glossary of Psychological Terms
From Gerrig, Richard J. & Philip G. Zimbardo. Psychology And Life, 16/e. Published by Allyn and Bacon, Boston, MA. Copyright (c) 2002 by Pearson Education. Reprinted by permission of the publisher.
http://www.apa.org/research/action/glossary.aspx?tab=4
(Disassociative did not appear in this Psych. glossary.)
A search of the APA site showed 148 hits for dissociative in the publications section. It also garnered 10 hits for disassociative. I didn't check all of the latter, but the ones I did look at were not used as a psych term, such as-
Q: Americans now recognize that terrorism is a real threat to their safety and are more anxious as a result. What implications does this have for clinicians in their practice and training?
A: To me it means that all of us must become specialists in dealing with anxiety. Anxiety is and will be part of what most, if not all, of our clients experience in addition to their other concerns. We need to teach our clients techniques such as deep breathing, muscle relaxation, thought stopping, thought redirection and identification of catastrophic thinking. Several colleagues have commented on how in the weeks following the attack their most disturbed clients came in and began the session just as they had ended the last session; as if nothing had happened in between. When that happens, one needs to think about a disassociative response.
(You wouldn't have wanted to use dissociative in the above statement.)
The APA site also garnered 4 hits for disassociate. None were used as a Psych. term as far as I could tell, they appeared in the context of data analysis, education goals, etc.
Law Dissociation and dissolution are terms that apply to changes in the legal standing of a partnership.
The RUPA altered this situation, providing that when certain events occur, such as a partner’s withdrawal from the partnership, the partnership is not necessarily dissolved. The RUPA introduced dissociation, whereby a partner can be dissociated from a partnership without the partnership ending. If a partner dissociates from a partnership, the partnership will not necessarily dissolve. The remaining partners can instead purchase the interests of the dissociating partner and continue partnership business.
https://partnerships.uslegal.com/partnership/dissociation-and-dissolution/
"Dissassociated person" is a term used to refer to problem gamblers in regulatory documents.
The Missouri Gaming Commission administers a List of Disassociated Persons for problem gamblers. The Problem Gambling List, created in 1996, provides problem gamblers with a method to acknowledge they have a gambling problem and to take personal responsibility for it by agreeing to stop visiting riverboat casinos in Missouri for the rest of their life, with a one-time option to petition to remove their name from the Problem Gambling List 5 years after placement on the Problem Gambling List. If a person has been on the Problem Gambling List for at least five years and comes off The List, and then wants back on, that person will be permanently placed on the Problem Gambling List without the ability to request another removal from the List.
The Problem Gambling List directs Missouri casino operators to:
remove Disassociated Persons from all direct marketing lists; refuse check cashing and credit privileges; and deny participation in player programs; and forfeit all points or complimentaries earned by the individual.
Except for the above RUPA term and the gambling term, I could not find any definitions or terms of art for either disassociate or dissociate in US legal dictionaries. But I noticed that disassociated person was very common when needing a catch-all term for everybody else who doesn't belong to the subject group.
So when should you use disassociate? Not very often, but there are some usages where it seems to be holding it's own, or even be preferred.
When talking about the relationship (or lack thereof) among associates.
When emphasizing the importance of the act of disassociating. I sense that disassociate is a more dynamic verb than dissociate - "tendency to disassociate", "desire to disassociate", "try to disassociate" etc.
In direct contrast to associate, ie. Associated And Disassociated Channel Signaling.
Mathematicians have a particular use - "disassociated variables".
Disassociated person seems to be the preferred way to characterize a survey respondent who didn't belong to the survey's target demographic.
"Disassociated persons" is a JW term for former members who have voluntarily left the Jehovah's Witness faith.