fastest

"That rope is dangerously loose. Make it fast!"

"That definition refers to "fast," not "fastest." "Fast" meaning "secure" or "fortified" is an archaic usage.

To give you a sentence for "fastest," meaning "moving with great speed," here's an example:

"The cheetah is the fastest land animal." "

"Even after years apart, they remained fastest friends, their loyalty to each other unchanged. "

"I am going to buy a fast car."

"a fast billiard table"

""My new computer has the fastest processor, so it can open big files very quickly." "

"The baby was fastest asleep after the long car ride. "

"All the washing has come out pink. That red tee-shirt was not fast."

"The student with the fastest memory in the class always remembers the formulas. "

"a fast woman"

"There must be something wrong with the hall clock. It is always fast."

"I think my watch is running fast."

"For indoor shots without a flash, use the fastest film you can find to capture enough light. "

"Hold this rope as fast as you can."

"He is fast asleep."

"The ambulance arrived fastest after the emergency call, reaching the scene in just a few minutes. "

"Do it as fast as you can."

""My watch is the fastest; it's showing 9:15, but it's really only 9:05." "

"Muslims fast during Ramadan and Catholics during Lent."