I am proud to be their little sister
Bhiksu may be literally translated as “beggar” or more broadly as “one who lives by alms”. It is philologically analysed in the Pāli commentary of Buddhaghosa as “the person who sees danger (in samsara or cycle of rebirth)” (Pāli = Bhayaṃ ikkhatīti: bhikkhu). He therefore seeks ordination in order to release from it. He is not thereby a Bhikkhu merely because he seeks alms from others; by following the whole code (of morality) one certainly becomes a Bhikkhu and not (merely) by seeking alms. Herein he who has transcended both good and evil, whose conduct is sublime, who lives with understanding in this world, he, indeed, is called a Bhikkhu.
A bhikkhu has taken a vow to enter the Sangha (Buddhist monastic community) and is expected to obey the Patimokkha, rules of monastic conduct (typically around 227 for a male, and 311 for a female) as set out in the Vinaya, although there are considerable local variations in the interpretations of these rules. A novice monk or nun in the Tibetan tradition takes 36 vows of conduct. The minimum age to take bhikkhu vows according to ruling is 20 years counted from the conception (i.e. appr. 19 years and 3 months from birth).