undercutting

verb

1. (form-of, gerund, participle, present)present participle and gerund of undercut

noun

1. An undercut; a cut in the lower part.

   “When there are undercuttings in the bass-relief, so that the plaster poured upon it would run into cavities, from which it could not be drawn up, but would break in them, these undercuttings must be filled up with plaster […]”