When it comes to the word "bystreets", there are several synonyms that can be used in its place. Admittedly, the term itself is fairly uncommon and rarely used in modern language. That being said, words like alleyways, side streets, backstreets, and laneways all effectively convey the same sense of a smaller or less traveled road that runs parallel to a main thoroughfare. Additionally, terms like alleys, passages, and pathways can also be used in a similar context. Ultimately, the choice of synonym will largely depend on the specific connotation or tone that the speaker or writer is aiming for when describing these narrow, winding routes.