Inter-penetrations can be described using several synonyms which help to explain the concept of one thing penetrating or permeating through another. Some synonyms include 'intertwining', 'intermingling', 'interweaving', and 'interlocking'. Each of these synonyms suggests a level of interconnectedness, where two objects or entities merge together in a seamless and often complex way. Inter-penetrations also imply an element of shared space or commonality, where one thing exists within another, creating a sense of overlapping. Therefore, these synonyms are useful in describing complex systems, relationships, and ideas, where multiple elements are at play, and their interaction is key to understanding the bigger picture.