tamrin@... wrote:

> I'm looking for a word, along the lines of homophone, homograph, etc,
> for "two letters that look different but have the same spoken sound".

That's "homophone" ("homo-" means "the same" and "-phone" means sound).
E.g., in most languages written with the Latin alphabet, <K> and <Q> are
homophonous to each other.

> I've found contrasting definitions for "homoglyph", but I believe the
> above would be its opposite. Assume the same system of writing for
> the two letters.

In fact it would. I never heard the term, but you can analyze it as "the
same (homo-) sign (-glyph)". The word normally used for this concept is
"homograph".

> If there is a different word used when crossing writing systems,
> I'd be interested to know it as well.

You can probably say they are "homologous" to each other
(http://www.bartleby.com/61/78/H0257800.html), or "homologues".

_ Marco