Since 97% of everyday weight scales (both in doctor offices and at home) measure our actual mass either in lbm and/or kg, and NOT force (lbf or N), then why does oxford choose to define weight to be relative? "a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing." Its not relative at all. It is an estimated absolute unchangeable value. My at home scale defines my "weight" to be 150 lbs (which is actually lbm not lbf although they dont say it). It takes into account and factors out earth gravity but still 150 lbm is my mass and if I were on the moon I would still be 150 lbm. So... its not relative at all.