The term 'develop slowly' can be described by three crossword solutions: gestate (7 letters), EVOLVE (6 letters), and INCUBATE (8 letters). Gestation is the process of carrying a fetus in the uterus from conception to birth. Evolution is the process of gradual change over time, often leading to the emergence of new species. Incubation is the process of keeping an egg warm until it hatches. All three of these processes involve a slow development over time.