The crossword solution for the term DEVELOP, AS AN EGG is INCUBATE. Incubation is the process of keeping eggs warm in order to promote hatching. This process is used by many species of birds, reptiles, and amphibians, as well as some fish and invertebrates. Incubation is also used in the artificial hatching of eggs in poultry farming. During incubation, the temperature and humidity of the environment must be carefully monitored to ensure successful hatching.