The story
Diminutives + -o.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A nickname of the surnames Mathieson, Mathison, Mathisen, Mathiesen, Matthiesen, Matthiessen, Matthisen, Mathiasen, Matthiasen, Matthiassen and similar. Full definition →
Diminutives + -o.
Etymology from Wiktionary, CC BY-SA 4.0.