not completely, but as a most important part synonym primarily, mainly We are chiefly concerned with improving educational standards. He's travelled widely, chiefly in Africa and Asia.Extra examples It is for his goalscoring exploits that fans chiefly remember him. Most American firms borrowed chiefly from banks. The dollar finished the day lower, chiefly because of expectations of a cut in US interest rates. The following chapter is chiefly concerned with answering these questions. The scientists cannot be held solely or even chiefly to blame.