The word 立马 is formed through a vivid metaphorical composition: it directly combines the character 立 (to stand) and 马 (horse), painting the literal image of "making a horse stand still". This concrete scene historically implied bringing a galloping horse to an immediate, abrupt halt. Over time, the phrase was abstracted to capture the essence of that moment, the instant transition from motion to complete stillness, thereby generating its core modern meaning of "immediately" or "at once", where the physical immediacy of the action transforms into a concept of temporal immediacy.