素食 (sùshí) literally means 'plain food' — 素 (sù) originally meant 'unadorned', 'simple', or 'not involving meat', and 食 (shí) means 'food' or 'to eat'. Over time, the term came to specifically refer to plant-based food that excludes all animal flesh (including meat, poultry, and fish), and often — though not always — excludes eggs and dairy as well. It is commonly used in dietary, ethical, religious (e.g., Buddhist practice), and health-related contexts.

In modern Chinese, 素食 is a neutral, standard noun — not slang or formal — and appears in restaurant names, menu labels, nutrition discussions, and lifestyle articles. While it emphasizes absence of meat, it does not automatically imply veganism; context or clarification (e.g., 纯素食 for 'strictly vegan') is often needed. The word reflects cultural values of moderation, purity, and compassion toward animals, making it deeply tied to both health consciousness and ethical choices.