锻炼 (duàn liàn) literally combines 锻 (duàn), meaning 'to forge' or 'to shape metal through hammering', and 炼 (liàn), meaning 'to refine' or 'to purify through heating'. Together, they evoke the image of strengthening something through repeated, disciplined effort—just as metal is made stronger by forging and refining. This metaphor extends naturally to physical exercise, mental training, or skill development.

The word is most commonly used as a verb meaning 'to exercise' (especially for health or fitness) or 'to train' (in a broader sense, such as training one’s willpower, language ability, or leadership skills). It carries a positive, intentional connotation—implying purposeful practice over time, not casual activity. While it can appear in noun phrases like 体育锻炼 (tǐyù duànliàn, 'physical exercise'), its core function is verbal and action-oriented.