-ency/-ancy vs. -ence/-ance

[sagehen]

>my colleague Beth Levin wrote on 9/29 to forward a query:
>
>> A computer science friend of mine wrote me the following and I
>> thought you might have some insight.  Is it in part a way of
>> creating a "jargon"?
>>
>> -----
>> My German-born colleague Torsten just asked me about the following:
>>
>> In technical papers, people often use the words "coherency" and
>> "relevancy" rather than
>> "coherence" and "relevance".  Why the replacement of "ency/ancy"
>> for "ence/ance"? How common is this?
>> -----
>
>the dictionaries i consulted treated -ncy as a variant of -nce, just
>as beth's friend did.
>
>the facts are complicated.  in a fair number of cases, only the -nce
>version occurs: confidence, resistance, persistence, benevolence,
>malevolence, insolence, independence. in some cases, only the -ncy
>version occurs: consistency, malignancy, fluency, constituency.  when
>there are pairs, sometimes the meanings are very clearly distinct
>(emergence vs. emergency), sometimes more subtly so (dependence vs.
>dependency), and sometimes there's considerable semantic overlap
>(coherence vs. coherency, relevance vs. relevancy, valence vs.
>valency).  when there's some overlap, the -nce version is more
>frequent, but the ratio of -nce to -ncy (in raw google web hits)
>varies quite a bit across the pairs:
>
>dependence : dependency - 1.44
>coherence : coherency - 1.56
>valence : valency - 11.47
>relevance : relevancy - 20.66
>
>for coherence/coherency, there's a technical sense of "coherence" in
>physics, but also specialized technical senses of "coherency" in
>several fields that are well represented on the web: "cache
>coherency" in computer science/engineering, and statistical
>"coherency" (paired with "consistency", an -ncy-only formation).  as
>far as i can tell, these -ncy technical uses don't vary with -nce at
>all; the form of the expressions is fixed.  so the ratio is low.
>
>but for valence/valency, the words are in competition pretty broadly,
>in technical senses in chemistry, linguistics, and mathematics.  the
>shorter and less complex -nce version then prevails by a wide
>margin.  (i'm inclined to use "valency" in talking about the argument
>structure of verbs, probably because i'm often contrasting valency
>with constituency, and "constituency" is a -ncy-only formation.)
>
>for relevance/relevancy, i find it very hard to see any
>specialization, and the shorter and less complex version prevails
>even more strongly.
>
>the longer and more complex versions might have some value on their
>own, however, just by virtue of their greater substance.  to some
>ears they might seem weightier, more formal, more serious, more
>technical.
>
>i suspect there's some literature on this, but i don't have the
>relevant part of my library to hand and so can't easily check out
>sources.  anyone have any lines on the issue?
>
>arnold, sending copies of this to beth and her friend
~~~~~~~~~~
No attempt to offer help on this, but as a footnote to your observation that
"......sometimes the meanings are very clearly distinct  (emergence vs.
emergency)":
I remember how startling I found it to hear "emergent" for the first time,
back in the late 50s, as referring to the underlying crisis of an
emergency. It was not meant as "developing," but as  qualifying the
situation for "emergency" status. This seems in the intervening years to
have become standard jargon in hospitals & related services.
A. Murie