transitive verb.
To underscore (written matter) with a single line to indicate italics.
transitive verb.
To emphasize.
The Century Dictionary and Cyclopedia
To print in italic type, or underscore with a single line in writing: as, to italicize emphatic words or sentences; in old books all names were commonly italicized. Also spelled italicise.
the GNU version of the Collaborative International Dictionary of English
verb.
To print in Italic characters; to underline written letters or words with a single line