Semi stitched implies either half stitched outfit in which styles are pre-constructed like shown in the image or has pre-defined neck styles, sleeve style on fabric with pre-defined sleeve length, neck depths & outfit length. In these type of apparels, either only side seams are left open which can be adjusted as per the bust size chosen.

Or it may have an un-stitched fabric with pre-constructed back and neck design and sleeve border.In rare scenario, the length of the blouse and sleeves can be altered, if the design permits.