Never-tiring is a word that describes someone or something that never gets tired or exhausted, but there are other synonyms for this expression as well. For instance, perpetual or unceasing can be used to describe someone or something that never tires or gets worn out. Similarly, tireless or indefatigable are also great synonyms for never-tiring, meaning that the person or thing in question always maintains their energy and drive. Another option is untiring, which conveys a sense of strength and determination that never wanes. Ultimately, there are many different ways to describe someone or something that can keep going without ever tiring out, making it a versatile and useful concept to explore further.