所需 (suǒ xū) literally means 'what is required' or 'that which is needed'. It functions as a noun phrase formed by the structural particle 所 (suǒ), which nominalizes the following verb, and the verb 需 (xū), meaning 'to need' or 'to require'. Together, 所需 transforms the idea of needing into a concrete noun referring to necessary items, resources, or conditions. It is commonly used in formal, written, or administrative contexts — such as medical instructions, official forms, or technical documentation — rather than casual speech.

This phrase often appears before nouns with 的 (e.g., 所需材料, 'required materials') or stands alone as a subject or object (e.g., 'Please submit all 所需'). Unlike the more colloquial 需要 (xūyào), 所需 carries a slightly more impersonal, procedural tone and frequently implies necessity imposed by rules, standards, or objective circumstances — especially in healthcare, education, or bureaucratic settings.