Spiritus asper

The spiritus asper ("rough breathing") is the mark of an initial aspiration in ancient Greek. It is written as an opening half moon on top of or to the left of an initial vowel and rho:

• ἁ- ἑ- ἡ- ἱ- ὁ- ὑ- ὡ-, ῥ-;
• Ἁ- Ἑ- Ἡ- Ἱ- Ὁ- Ὑ- Ὡ, Ῥ-.

The only situations when it can be written inside a word is :

• on top of a double rho in certain editions;
• when it represents a coronis resulting from a crasis implying a vowel bearing a spiritus asper.

The spiritus asper merely notes the presence of an initial consonant [h], which cannot be written otherwise when it is not initial: thus ὕμνος stands for humnos, "hymn", and ῥήτωρ for hrêtôr (or rhêtôr), "orator".

When a word begins by an initial grapheme which is a vowel not preceeded by an [h], the spiritus lenis ("soft breath") must be employed.