First or highest in rank, importance, value, etc. See also → main.
M.E., from O.Fr. principal, from L. principalis "first in importance," from princeps "first, chief, prince," literally "that takes first," from primus "first" + root of capere "to take."
Farin literally "foremost," from far-, Mid.Pers. fra-; O.Pers. fra- "forward, forth;" Av. frā "forth," pouruua- "first;" cf. Skt. pūrva- "first," pra- "before, formerly;" Gk. pro; L. pro; O.E. fyrst "foremost," superlative of fore, E. fore + -in superlative suffix.
principal quantum number
adad-e kuântomi-ye farin
Fr.: nombre quantique principal
In atomic physics, the first of a set of quantum numbers which describe an atomic orbital. Symbolized as n, it characterizes the size and energy of an orbital.