巩固 (gǒng gù) is a verb meaning 'to consolidate' or 'to reinforce' — to make something already existing stronger, more stable, or more secure. The character 巩 (gǒng) originally meant 'to strengthen with iron supports', evoking structural reinforcement; 固 (gù) means 'firm', 'solid', or 'stable'. Together, they emphasize the active process of deepening and securing an established foundation — whether knowledge, relationships, health, or political power.

This word is commonly used in formal, academic, or institutional contexts: reinforcing learning after study, strengthening health after illness, consolidating gains after reform, or fortifying alliances. It implies intentionality and effort, not passive maintenance. Unlike simple verbs like 加强 (jiā qiáng, 'to strengthen'), 巩固 carries a nuance of building upon something pre-existing — you consolidate what’s already there, not what’s brand new.