insure

insure /ɪnˈʃɚ/ verb
insures; insured; insuring
insure
/ɪnˈʃɚ/
verb
insures; insured; insuring
Britannica Dictionary definition of INSURE
[+ object]
1 
a  : to buy insurance for (something, such as property or health)
b  : to provide insurance for (something, such as property or health)
also : to provide (someone) with insurance
2 
US : to make (something) sure, certain, or safe : ensure

insure against

[phrasal verb]
1 
insure against (something) : to make (something bad) less likely to happen usually by planning and preparing
2 
insure (someone) against (something) : to protect (someone) from (something bad)