# sideline

/ˈsaɪdˌɫaɪn/ (US) · /sˈaɪdlaɪn/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/sideline
Updated: 2026-05-06

## Definition

the line that marks the side of a sports field. It also refers to a job or activity you do in addition to your main work.

For teachers: the boundary line extending along the side of a playing field; by extension, a secondary occupation or interest pursued alongside a primary career.

## Examples

- The coach stood on the sideline shouting instructions.
- She works as a lawyer but has a profitable sideline selling handmade jewelry online.
- While the athlete was forced to watch from the sideline due to injury, he began developing a business sideline in sports commentary that eventually became his full-time profession.

## Usage notes

- Often used in the plural ('the sidelines') when referring to the area just outside the field of play.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.