Collection: 1) Archival materials, regardless of form or media, organically created and/or accumulated and used by a particular person, family, or non-governmental organization in the conduct of personal or organizational activity.
2) An artificial accumulation of archival materials brought together on the basis of some characteristic (such as means of acquisition, creator, subject, language, media, form, name of collector) without regard to the provenance of the archival materials.
ca.: An abbreviation for the term "circa." Used if a date is approximate.
Circa: Abbreviated as "ca." Used if a date is approximate.
However, it's obviously a special case, and I've put forward one suggestion as to why that is; John Lawler has another which makes a lot of sense to me as well.
I think the OP was asking for a general rule - but we all know that there are always exceptions.
Similar indistinctions happen with words like "box", "church", "brush" and "fuzz". My husband and I started playing together a couple of years ago.We've had a steady girlfriend that we would have sex with regularly, and a few girls we've met with a couple of times for drinks out and then sex.I'm not a jealous person, but would not be happy if he ventured out on his own without me, but when we're having fun and playing together, I share him without any hangups.
I'm interested in the possibility of taking this further and actively looking for a woman to share our marriage with long term. mosses, dozes, mashes, mélanges, ditches, George's. To appreciate the distinction between voiceless and voiced, an intervocalic environment is best, e.g.