noun which may take the genitive case particle 'no'
Describes a person or worker who lacks skill or experience, often used in professional or training contexts.
未熟練の労働者には研修が必要だ。
Unskilled workers need training.
彼はまだ未熟練だが、やる気はある。
He is still inexperienced, but he is motivated.
熟練 means 'skilled' or 'experienced', the opposite of 未熟練.
Compound of 未 (mi, 'not yet') + 熟練 (jukuren, 'skill, proficiency'). The exact historical derivation is uncertain, but the components clearly indicate 'not yet skilled'.