unskilled person - a person who lacks technical training

blunderer, botcher, bumbler, bungler, fuckup, fumbler, sad sack, stumbler, butcher - someone who makes mistakes because of incompetence

slouch - an incompetent person; usually used in negative constructions; "he's no slouch when it comes to baseball"

incapable - (followed by `of') lacking capacity or ability; "incapable of carrying a tune"; "he is incapable of understanding the matter"; "incapable of doing the work"

inefficient - not producing desired results; wasteful; "an inefficient campaign against drugs"; "outdated and inefficient design and methods"

unqualified - not meeting the proper standards and requirements and training

unskilled - not having or showing or requiring special skill or proficiency; "unskilled in the art of rhetoric"; "an enthusiastic but unskillful mountain climber"; "unskilled labor"; "workers in unskilled occupations are finding fewer and fewer job opportunities"; "unskilled workmanship"

unskilled - not having or showing or requiring special skill or proficiency; "unskilled in the art of rhetoric"; "an enthusiastic but unskillful mountain climber"; "unskilled labor"; "workers in unskilled occupations are finding fewer and fewer job opportunities"; "unskilled workmanship"

bad - having undesirable or negative qualities; "a bad report card"; "his sloppy appearance made a bad impression"; "a bad little boy"; "clothes in bad shape"; "a bad cut"; "bad luck"; "the news was very bad"; "the reviews were bad"; "the pay is bad"; "it was a bad light for reading"; "the movie was a bad choice"

inadequate - (sometimes followed by `to') not meeting the requirements especially of a task; "inadequate training"; "the staff was inadequate"; "she was inadequate to the job"