Beta

google

ref

via Latin from Greek.

wiktionary

ref

From Ancient Greek βῆτα(bêta). Doublet of beth.

etymonline

ref

beta (n.)

second letter of the Greek alphabet, c. 1300, from Greek, from Hebrew/Phoenician beth (see alphabet); used to designate the second of many things. Beta radiation is from 1899 (Rutherford). Beta particle is attested from 1904. Beta male, pejorative term for a risk-avoidant, non-confrontational man perceived as a follower or supporter rather than a leader, is by 2005, transferred from zoology (birds, primates), where it is attested by 1962 (compare alpha male under alpha).