‘加倍’ literally combines ‘加’ (to add) and ‘倍’ (times/multiple), meaning to increase something by an equal amount — i.e., to double it. It functions primarily as an adverb modifying verbs (e.g., 加倍努力 — 'redouble one’s efforts') or as a verb meaning 'to double' (e.g., 产量加倍 — 'output doubled'). Unlike simple numerals like 两倍 (twice), ‘加倍’ emphasizes intentional, often effortful or intensified increase, especially in contexts of work, attention, speed, or intensity.

The word carries a slightly formal or literary tone and is common in written Chinese, news reports, and motivational speech. It does not mean ‘multiply by two’ in mathematical calculations (where 乘以二 or 翻倍 is preferred), but rather signals a purposeful escalation — whether positive (doubling care) or negative (doubling punishment). It’s rarely used with countable nouns alone; instead, it modifies actions or abstract quantities like effort, risk, or speed.