Adverb
In a sleek manner; smoothly.
Source: Webster's dictionarythe wet road was shining sleekly Source: Internet
Carr said, "She proves that women with filmy blue skin, lots of external tubing and bad teeth can be sleekly seductive." Source: Internet
The script's only guide on the appearance of the vessel was the line "the new Enterprise sleekly comes out of the nebula". Source: Internet