Sentence:  The natural anatomical and physiological defensive features of the upper respiratory tract , such as the turbinates of the nose and the <WSD>cilia</WSD> of the trachea and larger bronchi , are capable of impinging out the larger particles to which we are ordinarily exposed in our daily existence . 
Meaning of the word marked with <WSD> tags:  a hairlike projection from the surface of a cell; provides locomotion in free-swimming unicellular organisms