Wiktionary
unimpressively
adv. In a unimpressive manner
WordNet
unimpressively
adv. in an unimpressive manner; "she scored unimpressively low in the first round of the competition" [ant: impressively]
Usage examples of "unimpressively".
The pine forest straggled down unimpressively, the trees thirty and forty feet apart.
Then he bowed slightly as the older wizard came puffing unimpressively up the stairs.