apostrophus

noun4

1. •
   The symbol 'Ↄ', used in Roman numerals to indicate multiplication by 10.

   • In every multiplication with ten a fresh apostrophus is added; thus IↃↃ = 5000, IↃↃↃ = 50,000. — 1862
2. •
   (historical) An open notehead ( ~ ) or an apostrophe ( ' ) used as a neume to mark a low, unaccented syllable at the beginning of a phrase or a short quick syllable

   • You find not the apostrophus, and so miss the accent. Let me supervise the canzonet. — 1598
3. •
   (no longer used) The apostrophe symbol used to mark this elision.

   • The apostrophus or mark of contraction, is the same with the comma, onely the difference is of place; for, this stands not in the line, but over the upper part thereof, where the contraction is: — 1644
4. •
   (no longer used) The omission of a vowel or syllable from a word, usually indicated by the apostrophe symbol ( ' ). examples: 'til, can't

   • Vowels suffer also this apostrophus before the consonant h. — 1640