This came up at the book launch two days ago, when someone asked Margaret about the nautical definition of “sound” (her title being Voices from the Sound). She couldn’t say, nor could anyone else in the audience. In the interests of ready reference, i thought i’d put it down here. I don’t have my precious Canadian Oxford to hand (somebody who does, please plug it into the comments below!), but here’s some on-line elucidation:
Dictionary.com says, among several other meanings:
sound –- noun 1. a relatively narrow passage of water between larger bodies of water or between the mainland and an island: Long Island Sound.
2. an inlet, arm, or recessed portion of the sea: Puget Sound.
3. the air bladder of a fish.
Origin: bef. 900; ME; OE sund act of swimming; akin to swim
Excerpted from the Wikipedia page:
In geography a sound or seaway is a large sea or ocean inlet larger than a bay, deeper than a bight, wider than a fjord, or it may identify a narrow sea or ocean channel between two bodies of land (see also strait)….
There is little consistency in the use of ‘sound’ in English-language place names….
A sound generally connotes a protected anchorage.
I’m still looking for some official nautical definitions.
POSTSCRIPT: Compulsive research maven Heather delved into the Canadian Oxford for an entry that, alas, seems no more germane to Clayoquot or Barkley Sounds than either of the above. Here goes:
sound –- n. 1. a narrow channel or stretch of water, esp. one between the mainland and an island or connecting two large bodies of water.
2. an arm of the sea.
Greg Blee 
The entry in the “Canadian Oxford” isn’t any more helpful, but this will at least let me experiment to see if the tags you use in your entries will also work in the comments or whether they will just clutter up your very pretty blog. Here goes:
Hey, now I know how to make a pretty “blockquote” in a comment. Thanks, Greg!
You’re welcome, Heather. That’s what this blog is all about: A place for html hooligans to try out all their messy code experiments.