un ‧ im ‧ pressed /ˌʌnɪmˈprest/ BrE AmE adjective
[ Word Family: noun : ↑ impression , ↑ impressionism , ↑ impressionist , ↑ impressiveness ; adjective : ↑ impressionable , ↑ impressive ≠ ↑ unimpressive , ↑ impressionistic , ↑ unimpressed ; adverb : ↑ impressively , ↑ impressionistically ; verb : ↑ impress ]
not thinking that someone or something is good, interesting etc
unimpressed with/by
Board members were unimpressed with the plan.