suffix
Attaches to a quantity, number of times, or similar expression to mean 'only that much' or 'just that'. Often used in casual speech.
もう一杯こっきりしか飲んでいない。
I've only had one drink.
一度こっきりにしてください。
Please make it just once.
adverb
Obsolete mimetic adverb describing a sharp snapping sound or action. No longer in common use.
古い文献では、枝がこっきりと折れる様子が描かれている。
In old texts, it describes a branch breaking with a snap.