Overweight - this refers to a person who is between 25-30 pounds over the recommended weight for their height, or with a BMI between 25-29.9
Obesity - the condition of being considerably overweight, a person who is at least 30+ pounds over the recommended weight for their height, or have a BMI of 30+
Another bunch of terms that are important to learn are what are referred to as anatomical locations. These are terms which describe specific landmarks and locations on the human body. Actually several of these terms can be used for more than just the human body...also animal species now that I think about it!
Reference point - usually the center point of the body the following terms are all used in reference to this reference point
Superior - positioned above the reference point
Inferior - positioned below the reference point
Proximal - positioned nearest to the point of reference (eg. Shoulder)
Distal - positioned farthest from the point of reference (eg. Fingers)
Anterior/Ventral - front of the body
Posterior/Dorsal - back of the body (like a shark or dolphin's dorsal fin!)
Medial - positioned near the middle line of the body
Lateral - positioned toward the outer parts of the body
Contralateral - positioned on the opposite side of the body
Ipsilateral - positioned on the same side of the body
I'm gonna stop here for now, there are more terms to be had, but they shall be added along with pictures later on!