Spermatophore is a term that refers to a packet or capsule that contains spermatozoa, which is transferred by males to females during mating. Alternative synonyms for this word include sperm capsule, sperm packet, sperm ampulla, seminal capsule, sperm sac, or seminal vesicle. Other related terms include spermatheca, which is a female reproductive structure that stores sperm after mating, and spermatotheca, which is a similar structure found in some invertebrates. These synonyms and related terms are important for scientists studying the mating behavior of animals, as well as those interested in the reproductive biology and ecology of various species.