Shaving a Unibrow
Is it permissible for a man to shave his unibrow, or is it lo silbash? I’ve seen it quoted in the name of R’ Shlomo Zalman who permitted this for a boy who is in shidduchim. Perhaps it should be no problem as a woman only waxes or laser removes those hairs, not with an electric shaver.
If the purpose of trimming eyebrows is to avoid embarrassment, it is permitted to do so.
If the purpose is for beautification, it is better to avoid the practice, though it is not prohibited if it is the norm in his area for men to trim their eyebrows.
The Gemara (Nazir 59b) specifies pubic hair and armpit hair as being prohibited for men to shave. According to Rashba (Vol. 4, no. 90; see also Beis Yosef, Yoreh De’ah 181, and Bach 181:8-9), this prohibition applies to the entire body. However, the Rambam (Avodah Zara 12:9) writes that the prohibition applies specifically to places that it is the custom of women alone to shave. This is also the ruling of the Shulchan Aruch and Rema (Yoreh De’ah 182).
Therefore, if it is generally accepted for men to remove hair in a given part of the body, it is permitted to do so. For parts of the body where it is not generally accepted for men to remove hair, it is forbidden to do so for the sake of beauty, but it is permitted to do so if one requires this for purpose of medical treatment, or other non-beautifying purposes (see Darchei Moshe, Yoreh De’ah 182, Igros Moshe, Yoreh De’ah 2:61).