IPA: /ˈblʌfli/
KK: /blʌfli/
In a way that is bold or confident, often without being truthful or sincere.
He spoke bluffly, making promises he had no intention of keeping.
The word 'bluffly' is derived from 'bluff' (originating from Dutch 'bluf', meaning to boast or brag) and the adverbial suffix '-ly' (meaning in a manner of). Thus, 'bluffly' means in a manner that is boastful or braggart-like.
Think of someone who is 'boasting' ('bluff') and doing so 'in a manner' ('-ly'). This helps you remember that 'bluffly' describes a boastful way of acting.