1. Slyly and secretly
   "old line aristocratic diplomats underhandedly undermined the attempt...to align Germany with the Western democracies"
   - underhand

See also: underhand

• unusually
• unusualness
• unutterable
• unutterably
• unuttered
• unvaccinated
• unvalued
• unvaned
• unvanquishable
• unvanquished
• unvaried
• unvariedness
• unvarnished
• unvarying
• unveil
• unveiled
• unveiling
• unvendible
• unvented
• unventilated
• unverbalised
• unverbalized
• unverifiable
• unverified
• unversed