The term "upright bass" refers to a musical instrument that is also known as the double bass or contrabass. It is the largest and lowest-pitched instrument in the string section of an orchestra. The upright bass is played upright on its end, using a bow or plucking the strings with the fingers. It provides a deep and resonant sound in a musical ensemble.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Big member of the string section. Explanations are generated by AI and may be inaccurate.