幼儿 (yòu ér) literally combines 幼 (yòu), meaning 'young', 'immature', or 'juvenile', and 儿 (ér), meaning 'child' or 'son'. Together, they refer specifically to children aged approximately one to six years old — typically toddlers and preschoolers, before formal schooling begins. The term emphasizes early developmental stages and is commonly used in educational, medical, and parenting contexts.

This word carries a neutral, formal, or professional tone — you’ll hear it in discussions about early childhood education (幼儿教育), pediatric care (幼儿保健), or government policies on childcare. It’s not used for infants (婴儿) nor school-aged children (儿童 or 小学生). While 儿 can stand alone as a colloquial suffix (e.g., 小儿), 幼儿 is always a standalone noun and never used as a modifier before another noun (e.g., you wouldn’t say *幼儿学校 — instead, use 幼儿园).