ACCIACCATURA
Etymology
Noun
acciaccatura (plural acciaccaturas or acciaccature)
(music) A short grace note (theoretically taking no time at all), occurring on the beat occupied by the main note to which it is prefixed, one scale-step higher or lower than that main note. (Sometimes equivalent, therefore, to a short appoggiatura, but in Baroque music interpreted differently and more strictly.) Written as a note lighter in appearance, typically a quaver (eighth note), with an oblique stroke through the stem.
Source: Wiktionary
Ac*ciac`ca*tu"ra, n. Etym: [It., from acciaccare to crush.] (Mus.)
Definition: A short grace note, one semitone below the note to which it is
prefixed; -- used especially in organ music. Now used as equivalent
to the short appoggiatura.
Source: Webster’s Unabridged Dictionary 1913 Edition