Dictionary.com
definitions

nice-nelly

or nice-Nel·ly

[nahys-nel-ee]
adjective
  1. characterized by prudishness or excessive modesty: The entrance of his nice-nelly friend stopped the flow of risqué stories.
  2. being a euphemism; euphemistic: nice-nelly expressions.

Origin of nice-nelly

An Americanism dating back to 1920–25

nice nelly

or nice Nelly

[nel-ee]
noun
  1. a person who professes or exhibits excessive modesty, prudishness, or the like: too much of a nice nelly to have any fun.
  2. nice-nellyism(def 2).
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018