The word "deep" is commonly used to describe a significant distance or level of intensity. However, there are several synonyms that can be used in its place, depending on the context. Some common synonyms for "deep" include profound, extensive, thorough, intense, thoroughgoing, comprehensive, and in-depth. Alternatively, the concept of depth can also be conveyed through terms like bottomless, abyssal, impenetrable, unfathomable, or endless. In literature or poetic contexts, other synonyms might be preferred, such as soulful, contemplative, or introspective. Ultimately, the right synonym for "deep" depends on the intended meaning and tone of the sentence.