I hope I don't come across rude/ignorant, but what does "dyke" mean? I've never heard it before but apparently it's offensive? What does it mean? Thanks

A lesbian. But one with more manly charisteristics.

A dyke was a Dutch breakwater that held back the North Sea. There's a well-known story about a boy who put his finger in a dyke but it's a dangerous thing to do.  ANY boy trying to put his finger into a dyke these days would find himself in mortal danger.

In modern slang "dyke" is a pejorative slang term for lesbian. Sometimes it may refer to only the more masculine types but in Australia it is more politically correct not to discriminate. :(

We also have a group of motor-cycle riding lesbians who call themselves "Dykes On Bikes" but while they apply the term to themselves I think it is unlikely that they would accept the term from anybody else.

Another word for a cross-dresser.

A masculine lesbian basically