The term 'after epsilon letter' refers to the Greek alphabet, which is composed of 24 letters. The crossword solutions for this term are Zeta (4 letters), Zetas (5 letters), Psi (3 letters), DELTA (5 letters), SIGMA (5 letters), Phi (3 letters), and TAU (3 letters). Zeta is the sixth letter of the Greek alphabet, following Epsilon. Zetas is the plural form of Zeta. Psi is the 23rd letter of the Greek alphabet, DELTA is the fourth letter, SIGMA is the 18th letter, Phi is the 21st letter, and TAU is the 19th letter.