The phrase "stop dead" means to come to a sudden stop or to abruptly halt. Some synonymous phrases that can be used to convey a similar meaning include "halt abruptly," "come to a sudden halt," "freeze in one's tracks," "standstill," "cease instantly," and "abrupt cessation." Other synonyms for the phrase can depend on the context in which it is used. For example, in the world of technology, "crash" or "freeze" can be used to describe a sudden stop. Overall, there are a variety of phrases that can be used in place of "stop dead" depending on the situation and the connotation desired.