Sentence:  When making for the brook the falconer doth espy / One river plash or <WSD>mere</WSD> where store of fowl doth lie ... 
Meaning of the word marked with <WSD> tags:  A body of standing water, such as a lake or a pond. More specifically, it can refer to a lake that is broad in relation to its depth. Also included in place names such as (Windermere).