The Microsoft .NET Framework API¹ has a curiously named interface ILogicalThreadAffinative. According to their naming standard, namely concatenating capitalized meaningful English words into a single string, this represents something which is “logical thread affinative” (and the prefix “I” is for “interface”, which is irrelevant to this question), or, how I read it, affinative to a logical thread.

While the meaning of the “logical thread” is clear to the user², I am curious what could the word affinative mean, and is this not an invented word at all. To me, it looks like a two-stage suffixal defivation:

affine (adj.) > ?affinate (adj.) > ?affinative (adj.),

but I cannot find either of the latter two words in any dictionary, or even Google. I have been in this business for 30 years, give or take a few, and never heard them. Also, as documented, the concept is nothing more than being simply affine to a logical thread; the entity having this property simply “sticks” to the logical thread and follows it as it spans physical threads³.

Is the word affinative (and/or affinate) is, well, a meaningful word? And if it is, how is it different from affine?

Update: From @ZebraFish's answer it appears the correct spelling of the adjective is affinitive, and, by extension, that my own use of affine (including this post) in the sense “exhibiting affinity” is probably not correct or, at the very least, is not the best word choice.

¹ For the inquisitive but uninitiated, the acronym API, or Application Programming Interface, in this context means a very general set of programming functions for anyone writing a program to use. Usually, at this scale, when such a set is designed for literally tens of millions of users, the API design passes a long, stringent, iterative review for consistency, well-defined behavior and, not the least, naming. I would not even bother asking this question if the case in point was a set of narrow purpose functions developed by a small project (I have seen much worse), but this one is a general-purpose interface to a very popular, flagship platform from a very large company. This is why I am in doubt.
² Understanding what is a (logical) thread is probably not essential here. Simply speaking, it is merely a programmed sequence of actions that is logically causal and continuous, but physically executes on different parts of a computer or even different computers at different times.
³ To give an analogy, suppose you read a Kindle book on your phone, put it down, then later open the same book on a tablet and continue reading where you left off. The page number where you stopped and then continued goes along with, or is affine (or “affinative”??) to the “logical thread” of reading the book.

  • To me it looks like a spelling error. Should be "affinitive".
    – Hot Licks
    Commented Aug 11, 2018 at 1:18
  • @HotLicks Right though you may well be, OED nonetheless glosses affinitative with an extra syllababble.
    – tchrist
    Commented Aug 11, 2018 at 1:22
  • @tchrist - OED is just being syllie.
    – Hot Licks
    Commented Aug 11, 2018 at 1:26
  • @HotLicks I've just checked after seeing tchrist's comment, there seems to be "affinitative" and "affinitive" just as there are "preventative" and "preventive". Boy, is there a lot to answer for.
    – Zebrafish
    Commented Aug 11, 2018 at 1:27
  • @HotLicks Sorry, I misunderstood your point. You're right, it should be "affin-I-tive, not affin-A-tive. Edit: Or alternatively/alternately (hehe) affinitative.
    – Zebrafish
    Commented Aug 11, 2018 at 2:10

1 Answer 1


"affin-I-tive" yes, "affin-A-tive no, but see the the final note in my answer.

a. 1. Closely connected, as by affinity.
Webster's Revised Unabridged Dictionary

closely related: a situation affinitive to his own
Merriam-Webster Dictionary

An affinity, relationship, or connection.
1Characterized by affinity or mutual attraction.
2Closely connected or related.
Oxford Living Dictionaries

The last definition lists it also as noun, strangely enough. But it's in nearly all dictionaries I usually check. I'm surprised you didn't find it.

User tchrist pointed out there is also affinitative. I've checked definitions and it seems to be a variant spelling of affinitive.

Notice the same pattern of variant spellings in:

  • preventive/preventative (both acceptable)
  • interpretive/interpretative (both acceptable)
  • exploitive/exploitative (possibly some opposition to the first spelling)
  • authoritive/authoritative (likely opposition to the first spelling)

As to the word "affine", the only context I've heard this word used in is in the term "affine transformation" used in maths. Some definitions only list this term in a specialised context such as maths or anthropology. The following dictionaries do this:

Allowing for or preserving parallel relationships.
A relative by marriage.
Oxford Living Dictionaries

adj. Mathematics
1. Of or relating to a transformation of coordinates that is equivalent to a linear transformation followed by a translation. 2. Of or relating to the geometry of affine transformations.
American Heritage Dictionary

adj (Mathematics) maths of, characterizing, or involving transformations which preserve collinearity, esp in classical geometry, those of translation, rotation and reflection in an axis
Collins English Dictionary

Some dictionaries define "affine" in a generalised context and not as word specific to an academic field. However if you search in the above dictionaries for the past participle form of affine, that is, "affined", you'll get the following entries:

1. Linked by a close relationship.
2. Beholden to another; bound.
American Heritage Dictionary

closely related; connected
Collins English Dictionary

Two points I want to make. This phenomenon of a dictionary defining an inflected form of a verb, such as past participle, separate from the headword/lemma isn't all that common, but occurs when in its inflected form it has a meaning that can't easily be inferred from the meaning of the headword/lemma form. I can't think of a past participle example, but I can think of:

  • certify/certifiable

certifiable to mean crazy or insane may be listed as a separate entry from certify, which may not include the definition of "to declare insane". This is despite the common knowledge of what the suffix -able does. I'll add any better examples if I think of any.

Secondly, I'm sure you know that in certain fields words are used that won't be found in many dictionaries or are unknown by the general public, for example programmers use "performant". In this vein, given that the real word is "affinitive" and not "affinative", the "affinative" in "ILogicalThreadAffinative" may either be a mispelling or their own in-house spelling. I'm guessing this relates to Processor affinity which has to do with threads.

  • You missed affinitative.
    – tchrist
    Commented Aug 11, 2018 at 1:21
  • @tchrist Thanks, I'm kind of fleshing out my answer. Edit: Oh dear, there is affinitative and affinitive. I assume this follows the same pattern as preventative and preventive, both of which are acceptable. I'll try get to that.
    – Zebrafish
    Commented Aug 11, 2018 at 1:23
  • Thank you, that makes sense now! Never heard this word. It should be a denominal adjective from affinity then. Perhaps my own use of affine in the same sense is not strictly correct.
    – user173639
    Commented Aug 11, 2018 at 1:26
  • The performant I know, and researched it's origin a while ago. Curiously, it is also traceable to the software engineering jargon at Microsoft. Usually programs are performant, not programmers.
    – user173639
    Commented Aug 11, 2018 at 1:29
  • The only reason that “programmers” use performant is because they are caught up in corporate business jargon which casts an illusion that it’s both hip and also meaningful in some special way that “performs well” or simply efficient is not.
    – tchrist
    Commented Aug 11, 2018 at 1:53

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