The antonyms for the word "bulges out" include "recessed," "concave," "sunken," "hollow," "deflated," "collapsed," and "shrunk." These words indicate a depress or dip instead of a protrusion or extension. "Recessed" means to set back or sunk below a surface, while "concave" refers to a surface that curves inward. "Sunken" means to be submerged or sink below a level, and "hollow" refers to an empty space within an object. "Deflated" and "collapsed" imply a loss of air or structure respectively, while "shrunk" means to become smaller in size or volume.