左侧 literally means 'left side' and is a compound noun formed from 左 (zuǒ, 'left') and 侧 (cè, 'side' or 'flank'). Unlike the more casual 左边 (zuǒbiān), 左侧 carries a slightly more formal or spatially precise tone — it’s often used in directional instructions, technical descriptions, anatomical references, or official signage where exact positioning matters. It implies a fixed reference point (e.g., the observer’s perspective or an object’s orientation), and is commonly paired with words like 'of', 'on', or 'at' in English translations.

You’ll encounter 左侧 frequently in contexts like driving directions ('turn left at the intersection'), architectural plans ('the door is on the left side of the corridor'), medical reports ('a lump was found on the left side of the neck'), or public notices ('exit located on the left side'). While both 左边 and 左侧 mean 'left side', 左侧 feels more objective and less conversational — think maps, manuals, or safety guidelines rather than everyday chat.