unsystematic

adjectives

lacking systematic arrangement or method or organization
"unsystematic and fragmentary records"; "he works in an unsystematic manner"
unsystematic
antonym
systematic
see also
lacking order or methodical arrangement or function
"a disorganized enterprise"; "a thousand pages of muddy and disorganized prose"; "she was too disorganized to be an agreeable roommate"
disorganised, disorganized
see also
contrary to rule or accepted order or general practice
"irregular hiring practices"
irregular