On Sun, 22 Aug 2010 01:08:44 -0500, Eric Christopherson <[log in to unmask]>

>Reviving a dead thread. I was looking up the word _mains_ (referring to AC
power on the right side of the pond) at
>The etymology given connects _main_ with OE _męgen_, which I know
_might(y)_ is also related to.
>Back to the reason I was looking up _mains_: is it used with a singular
verb? And what is the etymology of that specific sense of _mains_ (i.e. why
does it have -s)? 

The OED suggests no more satisfying reason than just that the principal
power lines tend to be spoken of collectively:
MAIN n.1 8. A principal channel, duct, or conductor for conveying water,
sewage, gas, or (usu. in pl.) electricity. Cf. MAIN adj.2 5a, MAINSBORNE
adj. Also in pl.: the public supply of water, (or electricity, etc.)
collectively. Also fig. 

Funnily, of their 15 citations, none of them has "mains" as the subject of a

Anyway, beyond that, this is the plain old inherited word "main", as you
saw.  OED calls this use a re-nominalisation of the adj., which itself is
"[p]robably partly < MAIN n.1 in compounds in Old English; partly < the
cognate early Scandinavian adjective (compare Old Icelandic meginn, megn
strong, powerful), and also < the corresponding early Scandinavian noun in
compounds (see below).".  It was the adj. that originally underwent the
development 'strong, powerful' > 'principal'.  

>The site shows a sense "the main or home farm of a manor, as where the
owner lives; manse."; perhaps it's related to that. _Manse_, in turn, comes
from ML _ma:nsus_ "farm, dwelling", which I believe is related to

Yeah, separate etymology.  OED: "Shortened < the plural of DEMESNE n. 3",
where ultimately "Demesne is thus a differentiated spelling of the word
DOMAIN", tracing to "L. dominic-us, -um of or belonging to a lord or master,
f. dominus lord".  The association with words from L. _mansio_ is old,
though, and probably explains the <s> in the spelling.