What is the X in X-mas?
Old English leornung "learning, study," from leornian (see learn). Learning curve attested by 1907.
Old English leornian "to get knowledge, be cultivated, study, read, think about," from Proto-Germanic *liznojan (cf. Old Frisian lernia, Middle Dutch leeren, Dutch leren, Old High German lernen, German lernen "to learn," Gothic lais "I know"), with a base sense of "to follow or find the track," from PIE *leis- "track." Related to German Gleis "track," and to Old English læst "sole of the foot" (see last (n.)).
The transitive sense (He learned me how to read), now vulgar, was acceptable from c.1200 until early 19c., from Old English læran "to teach" (cf. Dutch leren, German lehren "to teach," literally "to make known;" see lore), and is preserved in past participle adjective learned "having knowledge gained by study." Related: Learning.
learning learn·ing (lûr'nĭng)
The act, process, or experience of gaining knowledge or skill.
Knowledge or skill gained through schooling or study.
Behavioral modification especially through experience or conditioning.