There are several synonyms for the acronym "BTOW", which stands for "By The Way". Some alternative expressions to convey a similar meaning include "Incidentally", "As an aside", "Speaking of which", "In passing" and "While we're on the subject". "By the by" and "By way of reminder" could also be used as alternative phrases to add variety to the conversation. These expressions help to transition between topics or add additional information. In conversation and online communication, it is useful to have a range of synonyms for common expressions to avoid repetition and keep the conversation interesting.