the world > physical sensation > taste and flavour > sourness or acidity > make sour [verb (transitive)] > make bitter (3)
To make sharp (in various transferred senses of the adjective). = sharpen, v. 2b.
transitive. To make bitter, impart a bitter taste to. Now rare in literal sense.
To make sharp or sharper (in various transferred and figurative senses of the adjective). Now… To give an acid flavour or quality to, to make (a…