Definition of the word buck up

The origin of the expression "buck up" can be traced back to the mid-19th century in British English. It initially meant "to make oneself more attractive," particularly referring to young men preventing themselves from slouching or appearing unattractive. The origin of this usage can be linked to a person's physical posture and behavior, with "buck" representing a male deer, which appears alert and erect. The phrase "Buck up, my lad, she's looking at you" was uttered as a word of encouragement to men in order to help them create a more attractive appearance in front of women. Over time, the meaning of "buck up" altered to become a phrase urging someone to be courageous and optimistic in the face of adversity. It now regularly appears in modern-day English as common slang used to advise people to remain hopeful, strong, and steadfast when facing difficult situations. In summary, "buck up" stems from the phrase "make oneself more attractive by appearing alert and erect, like a male deer," and has since evolved into an expression of encouragement to remain brave and optimistic amid hardships.