interlining I. in·ter·lin·ing\“+|liniŋ\noun Etymology: Middle English, from gerund of interlinen, enterlinen to interline — more at interline : interlineation II. in·ter·lining\“+\noun Etymology:inter- + lining 1.: an inner lining (as of a coat or jacket) consisting of a warm or firm fabric shaped and sewn between the ordinary lining and the outside fabric 2.: any fabric used for making interlinings