To constrain, or to confine within set limits.(verb)
To secure as if with a rope or hook.(verb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "tie down" in a sentence
"Two-point restraints bind two extremities usually arms, and four-point restraints tie down all four extremities."
"The Camel Corps scrambled to tie down their camels and build parapets of saddles and store boxes."
"Spee could/would continue to cause damage and destruction to enemy shipping as long as possible in order to tie down the greatest possible enemy forces in defence of trade. la pursuing this course the instructions from Germany that the enemy must obtain no prestige from the destruction of any of the panzerschiffe must be borne in mind."