Webster's Revised Unabridged Dictionary · 1913

Chiefly

Chiefly , adverb

1.
In the first place; principally; preeminently; above; especially.
Search through this garden; leave unsearched no nook; But chiefly where those two fair creatures lodge. — Milton
2.
For the most part; mostly.
Those parts of the kingdom where the... estates of the dissenters chiefly lay. — Swift