Sandhya

(“union”) Morning and evening twilight,
the two transitional times between day
and night and thus, metaphorically, the
times when day and night are united.
The word also often denotes certain
rites performed daily at morning, noon,
and evening, the three times when different parts of the day are in union.
These rites are prescribed in the dharma literature as mandatory for all
twice-born men, that is, all men from
the brahmin, kshatriya, or vaishya
groups who have undergone the adolescent religious initiation known as the
“second birth.” At present time these
rites are performed only by the most
orthodox brahmins.