If "cloak" means to cover or hide:
* Reveal
* Expose
* Unmask
* Disclose
* Uncover
* Show
* Display
If "cloak" refers to the garment itself:
* Bareness (lack of covering)
* Openness (lack of concealment)
* Exposure
* Dress (something that's worn but not necessarily for concealment)
If "cloak" means a disguise or pretense:
* Honesty
* Truth
* Transparency
* Authenticity
Let me know if you have a specific sentence in mind, and I can give you a more accurate antonym!