noun
concatenation
kun-kat-uh-NAY-shun/kənˌkætəˈneɪʃn/
The joining of things into a connected series.
The concatenation of colored chain sections creates one continuous length.

Etymology
Together and chain first described the state of being linked together. The noun then came to name the resulting series itself: things united in sequence like links in a chain.
In context
so in the regular expression language that clean invented indeed it is a concatenation but concatenation often omit its operator
More examples
- A concatenation of small mistakes delays the project.
- The software uses concatenation to join first and last names.
- The poem reads like a concatenation of overheard conversations.
Forms
concatenation · concatenations
concatenate verb — To join things in a connected series.
Similar words
- linking
- Linking emphasizes connections without requiring a single ordered series.
- combination
- Combination brings things together without necessarily preserving a sequence.