- In a diphthong, the oxia is written atop the second of the two vowels.
- The oxia is virtually identical in form to the Latin-script acute accent: ⟨ ´ ⟩. Its Modern Greek derivation, the tonos, also very closely resembles it in most cases.
From the Ancient Greek ὀξεῖᾰ (okseia), an elliptical use for ἡ ὀξεῖᾰ προσῳδῐ́ᾱ (hē okseia prosōdíā, “the acute accent”) — ἡ (hē, the nominative feminine singular form of ὁ, ho, “the”, the definite article) + ὀξεῖᾰ (okseia, the nominative feminine singular form of ὀξῠ́ς, oksus, “sharp”, of sound “shrill”, of tones “high-pitched”) + προσῳδῐ́ᾱ (prosōdiā, “variation in pitch of the speaking voice”, “pronunciation of a syllable on a certain pitch”, “a mark [i.e., a diacritic] indicating normally unwritten differences of pronunciation, viz. vowel quantity, breathing, and pitch”).