Louis Armstrong’s most associated nickname is Satchmo.
The name is commonly explained as a shortened form of “Satchel Mouth,” a nickname referring to Armstrong’s unusually wide, expressive smile. “Satchmo” became strongly linked with his public identity as his international fame grew, especially from the 1920s onward.
Armstrong was born in New Orleans in 1901 and became one of the most influential figures in jazz. His trumpet playing, rhythmic ideas, and gravelly singing helped move jazz toward a soloist-centered art form. He also helped popularize scat singing and became a major international entertainer.
“Satchmo” is sometimes confused with “Pops,” another nickname Armstrong used and that musicians and fans associated with him. “Satchel Mouth” is the longer form, while “Satchmo” is the canonical short form most often used in biographies and reference works.