The combination of 消 (xiāo) and 磨 (mó) creates a vivid image. To 消磨时间 is to “consume and grind down time,” as if time itself were a physical object that you are slowly wearing away until it's gone. This is a much more descriptive and passive image than the English “kill time.”
In many Western cultures, especially in the US, the phrase “time is money” is deeply ingrained. “Killing time” can be seen as a negative, almost wasteful act. In Chinese culture, the perspective can be more fluid. 消磨时间 (xiāomó shíjiān) isn't as inherently negative as “wasting time.” It captures a state of being that is a common part of life: waiting, being idle, or simply lacking direction for a short period. The term reflects a certain acceptance of these empty moments. The imagery of “grinding” suggests a patient, enduring process rather than a violent “killing.” It contrasts with the concept of 悠闲 (yōuxián), which means “leisurely and carefree.” 悠闲 is a positive, desirable state of relaxation and enjoyment. You might spend a 悠闲 afternoon reading in a park. However, if you were stuck at a train station for hours with nothing to do but scroll on your phone, you would be 消磨时间. The former is a choice to enjoy free time; the latter is often a necessity to endure it.
This term is very common in everyday, informal conversation.