Bismillahi Al-Rahmani Al-Rahim

Lesson 04 -- Wudu And Sexual Desire

1) What is the exact definition of 'sexual desire' for
a male and female?

2) If a person touches a member of the opposite sex
with the intention of achieving 'sexual desire', but
the individual fails in this pursuit (assuming here
that the definition to the above question is physical
- i.e. an erection for the man - and not just an
inner, lustful feeling), will the 'toucher' (laamis)
lose their wudu? or is the mere intention, accompanied
with succesfully touching the other person, sufficient
to nullify the 'toucher's' wudu?

Touching a member of the opposite sex invalidating wudu is hinged upon the presence of shahwah, intended or unintended. When shahwah is not found then wudu is still valid. Most late books--including Al-Muqni`, Dalil Al-Talib and Ikhsar Al-Mukhtasarat--use the phrase "li shahwatin". Kashf Al-Mukhaddarat  that Al-Wajiz  uses "bi shahwatin" and that this is better since it indicates that what is intended is  touching accompanied by shahwah.

As for what is meant by shahwah, Hashiyat Al-Lubadi states that what is meant by the phrase "li shahwatin"  here is "li lidhdhatin". The first, shahwah, is desire and excitement. The second, lidhdhah, is pleasure. So if someone touches a member of the opposite sex and experiences some type of pleasure, the wudu has been invalidated. This is something subjective, and it is not necessary that there be outward signs. Here there is either absence of pleasure or various degrees of pleasure. In any case, it is still recommended to make wudu after touching a member of the opposite sex even when there is no pleasure.

And Allah knows best.

wa al-salamu `alaykum