Sentence:  Consider a shear <WSD>field</WSD> with a height of H and a cross-sectional area of A opposed by a manometer with a height of h ( referred to the same base as H ) and a cross-sectional area of a . 
Meaning of the word marked with <WSD> tags:  the space around a radiating body within which its electromagnetic oscillations can exert force on another similar body not in contact with it