■ noun
1》 Music, Brit. a note having the time value of two crotchets or half a semibreve, represented by a ring with a stem.
2》 a small bronze or silver ancient Roman coin.
3》 one sixtieth of a fluid drachm, about one drop of liquid.
4》 (in calligraphy) a short vertical stroke, as in the letters i , m , n , u .
Origin
ME: from L. ~a , from ~us 'smallest'.