No, they do not mean as a sacramental ceremony in church. They mean marriage as they sign a piece of paper and the government recognizes them as being married.
And sorry, but throughout history, words are redefined all the time. Either the meaning changes slowly in everyday speech, or some event redefines a certain meaning or use of a word.
Prop 8 wasn't about forcing a church to marry same-sex couples. It was about the ridiculous archaic belief that the word marriage should only apply to heterosexual couples. As far as I'm concerned, the word "marriage" (and the root "marry") is just as applicable to same-sex couples as heterosexual couples. The word "marry" can and is used for denoting that 2 substances/ideas/objects/whatever are somehow joined.
http://dictionary.reference.com/browse/marry6. to combine, connect, or join so as to make more efficient, attractive, or profitable: The latest cameras marry automatic and manual features. A recent merger marries two of the nation's largest corporations.
7. Nautical.
a. to lay together (the unlaid strands of two ropes) to be spliced.
b. to seize (two ropes) together end to end for use as a single line.
c. to seize (parallel ropes) together at intervals.
10. (of two or more foods, wines, etc.) to combine suitably or agreeably; blend: This wine and the strong cheese just don't marry.
Prop 8 was all about homophobic jackasses trying to use the word of the law against homosexual people. It was all about leaning too heavily on the specific wording of the law fore the purpose of denying homosexual people the right to marry.
There's a reason for the constitutional amendments: to deal with new issues that may come up that weren't foreseen when the original constitution was drawn up, and this is one of them.
