If "check" means to examine or verify:
* Ignore
* Overlook
* Disregard
* Neglect
If "check" means to stop or hinder:
* Encourage
* Promote
* Support
* Facilitate
If "check" means to mark something off a list:
* Add
* Include
* Insert
If "check" refers to a financial transaction:
* Deposit
* Credit
If "check" means to restrain or control:
* Release
* Free
* Unleash
To give you the most accurate antonym, please provide the sentence or context where you're using the word "check".