冷不防

by surprise; suddenly

冷的英语翻译：

cold; cold in manner; shot from hiding
【医】 algor; cry-; crymo-; cryo-; krymo-; kryo-; psychro-

不的英语翻译：

nay; no; non-; nope; not; without
【医】 a-; non-; un-

防的英语翻译：

defend; guard against; prevent