"Foot diameter" refers to the measurement of the widest part of something, which is equal to the distance across that thing, from one end to the other, when those two ends are exactly opposite each other. Full definition
The park was packed, but there was an area of at least one hundred feet diameter with a woman and her sign in the middle, and no one else in the area. (redeeminggod.com)
The resort's heated swimming pool offers stunning ocean views and our 18 - foot diameter children's pool is ideal for small children. (thesandstc.com)
However the real thing, as shown here, costs a little over US$ 5,000 for a 22 foot diameter version with an insulated skin. (treehugger.com)