chiefly
/ˈtʃiːflɪ/adverb
1- mainly主要地：
he is remembered chiefly for his organ sonatas.
他主要因管风琴奏鸣曲留名于世。
1.1
- for the most part; mostly.大部分; 大多数：
a faction that consisted chiefly of communists.
主要是由共产主义者组成的派别。