IPA: //ʌnˈbɪznəsˌlaɪk//
KK: /ʌnˈbɪznəsˌlaɪk/
Not behaving in a professional or efficient manner, especially in a business context.
His unbusinesslike approach to the project caused delays and confusion.
Unbusinesslike → It is formed from "un-" (meaning not) and "business" (from Old English "bisignis", meaning occupation or state of being busy) and "-like" (meaning resembling or characteristic of). The word describes a manner that is not characteristic of proper business conduct.
Think of 'not' ('un-') being added to 'business' to describe a way of acting that doesn't resemble proper business behavior.