IPA: //ʌnˈskɪlfəl//
KK: /ʌnˈskɪlfəl/
Not having the ability or skill to do something well; lacking proficiency or expertise.
His unskillful attempts at painting made the artwork look messy.
Unskillful → It is formed from "un-" (meaning not) and "skillful" (from Old English "sciell" meaning ability or skill, combined with "-ful" meaning full of). The word "unskillful" means not full of skill or lacking ability.
Think of 'not' ('un-') having 'skill' ('skillful') — that's why unskillful means lacking skill.