social structure
ब्रह्मचारिन् brahmacārin
brahmacārin
root brahman + √car — moving in / dedicated to brahman — one who lives the celibate-student life
One who has taken the vow of celibate study; the first of the four classical āśramas (life-stages). By extension, anyone under a vow of celibacy.
The brahmacārin is the student in the first of the four classical āśramas (life-stages): brahmacharya (celibate study), gṛhastha (householder), vānaprastha (forest-dweller), saṁnyāsa (renunciation). The student lives with a teacher, takes alms, abstains from sex, and absorbs Vedic learning before — usually in the late teens — graduating into householder life.
By extension the term applies to anyone under a vow of celibacy regardless of age. Bhīṣma’s vow makes him a lifelong brahmacārin even though he is a prince; the unusualness of the situation is the engine of the dynastic crisis that follows.