Definitions

1. verb

to make dull or less interesting; to make something less intense or less effective

“The long, dull days began to dullify her spirits.”

2. verb (transitive)

to make dull or less sharp; to blunt something

“The constant rain began to dullify the edge of the knife.”

3. verb (intransitive)

to become dull or less interesting

“The excitement of the trip began to dullify as the days went by.”