Does lowering the gaze mean not seeing anything of women, even if it's a part like a man from behind when looking at the ground?

The Islamic Sharia (definition) has prohibited looking at non-mahram (definition) women in order to protect souls, preserve honor, and block pretexts. Allah Almighty says: "Tell the believing men to reduce [some] of their vision and guard their private parts." (An-Nur: 30). Only a sudden glance is excused, as the Messenger of Allah, peace and blessings be upon him, said to Ali, may Allah be pleased with him: "O Ali, do not follow a glance with another glance, for you are allowed the first, but not the second." If a Muslim needs to be in a place where there are women, he must lower his gaze and avert it whenever it falls upon something unlawful to look at. Allah does not burden a soul beyond its capacity.