What is "unassertive"

Usage examples of "unassertive".

His clear-cut features, something too sharply defined for absolute regularity, with the unassertive effect of his straight auburn hair, his deliberate, contemplative glance, his reserved, high-bred look, the quiet decorum of his manner, were not suggestive of the tumult of his inner consciousness, and the unresponsiveness of his aspect baffled Briscoe.