The numeral 'one' serves both as a simple count and as emphasis: 'one single ruler let there be,' Homer declares. Strengthened forms like εἷς οἶος mean 'one alone.' The word can stress uniqueness, unity, or singularity. Its oblique forms (genitive ἑνός, dative ἑνί) continue from an Indo-European root related to Latin 'sem-' (as in 'simple'). The feminine μία comes from a different stem than the masculine/neuter, preserving ancient morphological complexity.