A motto was a phrase selected by a group or organization to define their mission or worldview.
"Infinite diversity in infinite combinations" was a Vulcan motto. (ENT: "The Andorian Incident")
According to the Minosian peddler hologram, the motto of Minos was "peace through superior firepower". (TNG: "The Arsenal of Freedom")
Prior to becoming a tailor, Garak lived by the motto, "Never let sentiment get in the way of your work." He felt it was a cliché, but a true one. (DS9: "Profit and Loss")
In 2373, Doctor Julian Bashir adopted the motto, "Show no fear", when moving through the Klingon presence on Deep Space 9's Promenade. (DS9: "Apocalypse Rising")
The Cardassian Third Battalion's motto was "Death to all." Later in 2373, Crewman Pechetti warned fellow DS9 visitors to Empok Nor of that ominous fact after hearing that two of the battalion's members were loose on the station. (DS9: "Empok Nor")
The motto of the Jem'Hadar soldiers was "Victory is life." (DS9: "What You Leave Behind")