A board foot is one foot long, one foot wide and one inch in thickness. Checking the Waste Mary Huston Gregory This is usually expressed in pounds per thousand board feet, a board foot being considered as one-twelfth of a cubic foot.
Sibilance is a manner of articulation of fricative and affricate consonants, made by directing a stream of air with the tongue towards the sharp edge of the teeth, which are held close together; a consonant that uses sibilance may be called a sibilant, or a strident.
Hum is defined as to make a low, steady sound like a motor, to be busy, or to sing with closed lips. 1  When a fan whirs quietly in the background, this is an example of when the fan hums.  When a cafeteria has a low, steady sound of chatter, this is an example of when the cafeteria hums.