I read the question submitted by an individual who asked about female homosexuality. He was answered by a Mrs. Tzivie Greenberg I believe. With all do respect, I believe her answers to this issue were very incomplete. Although Lesbianism is not mentioned in the Torah, Rashi discusses that this is what the ancient Egyptians practiced. The posuk warns us not to follow in this path of "K'maaseh eretz Mitzrayim." Furthermore, this issue is discussed in Gemara as well, namely Yevamos 76a with rashi, interpreting the term of "Mesolelot." There is also a Machlokes if this prohibition is Biblical or Rabbinic. Further information is available in the Encyclopedia of Jewish Medical Ethics, authored by Avraham Steinberg, published by Feldheim, page 937, with notes there for further information. In my opinion, when someone asks a question of such controversy, the appropriate sources should be cited to clarify the matter, rather than simply giving a yes or no answer and saying it is not part of the Torah's lifestyle. Thank you.

It is a machlokes between the Rambam (Issurei biah 21 or 22 - I don't have it in front of me) and the Perischa in Ewen Haeser 20 if it is an issur mideoraissa. The Rambam says it is a "Lav Schebichlalut" (-Generalised prohibition) of "Kemaaseh erez Mizrajim" and is therefore not punishable, but is still mideoraissa. The Perischa says it's an "Assmachta" and therefore only a rabbinical prohibition.