完善 (wán shàn) means 'comprehensive, well-developed' and focuses on a system or process being complete and fully functional, with no missing parts. It differs from 完美 (wán měi 'perfect'), which implies flawless quality, and from 发达 (fā dá 'developed, prosperous'), which emphasizes economic or physical growth. As a verb, it means to make something more complete or effective.