EPSILON

[ 'ɛpsɪlɒn , ɛp'sʌɪlɒn ]

■ noun the fifth letter of the Greek alphabet ( Ε , ε ), transliterated as ‘e’.

↘[as modifier ] denoting the fifth in a series of items or categories.

Origin

Gk, 'bare or simple E', from psilos 'bare'.