suffix
leaving something in an improper state
Attaches to the -masu stem of a verb. Indicates that something is left undone, open, on, or in an undesirable state, often with a nuance of neglect or carelessness.
ドアを開けっぱなしにしないでください。
Please don't leave the door open.
仕事をやりっぱなしで帰ってしまった。
He left work unfinished and went home.
suffix
continuously; keep doing
Attaches to the -masu stem of a verb. Describes an action continuing without pause, often with a sense of relentlessness or excess.
昨日から雨が降りっぱなしだ。
It has been raining nonstop since yesterday.
彼は一時間もしゃべりっぱなしだった。
He kept talking for a whole hour.