But the reason that "gay" now has only one meaning is because the straight community has deliberately stopped using it in its original sense, rather than risk any ambiguity. Many (most?) people are happy to continue to use "high", "weed" etc in the broader senses, but wary of using "gay" in its earlier, more general sense in case it is misunderstood or causes offence.

That's their choice. If people feel that the link with homosexuality has tainted the word, that's their problem. No one has "hijacked" the word or forbidden anyone else from using it as they wish - it's still there for the taking.

Marje