(Greek: glossa, tongue)
Brief notes which explain difficult words or passages of Holy Writ.
Glosses in older works were written either on the margin or between the lines.
Modern works use footnotes exclusively. The most famous glosses are the "Glossa Ordinaria" of Walafrid Strabo (died 849), and the "Glossa Interlinearis" of Anselm of Laon (died 1117).
At times glosses found their way into the text.
Thus "For thine is the kingdom and the power and the glory, forever. Amen." is a liturgical gloss in King James's Bible (Matthew 6).
New Catholic Dictionary