Sentence:  `` In addition to the usual tools , I make constant use of cleansing tissue , not only to wipe my brushes , but to mop up certain <WSD>areas</WSD> , to soften edges , and to open up lights in dark washes . 
Meaning of the word marked with <WSD> tags:  a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography)