Noun
The portion of a wind instrument through which the air is blown.
(mining, historical) A wind road; a ventilation route in a mine.
Source: en.wiktionary.orgWolfe Since the size and direction of the tin whistle's windway is fixed, like that of the recorder or fipple flute, it is necessary to increase the velocity of the air stream. Source: Internet
The top of the instrument is damaged: only a cut side of the windway survives, and the block has been lost. Source: Internet