1 (in botany)
a A dry fruit that releases its seeds when ripe; it is formed from several fused carpels and contains many seeds. The seeds may be dispersed through pores (as in the poppy), through a lid (as in plantain), or by the splitting and separation of the individual carpels (as in the crocus). Various other forms of capsules include the silicula and siliqua.
b The part of the sporophyte of mosses and liverworts in which the haploid spores are produced. It is borne on a long stalk (seta) and sheds its spores when mature (see peristome).
2 (in microbiology) A thick relatively rigid gelatinous layer completely surrounding the cell wall of certain bacteria (see glycocalyx). It appears to have a protective function, making ingestion of the bacterial cell by phagocytes more difficult and preventing desiccation.
3 (in animal anatomy)
a The membranous or fibrous envelope that surrounds certain organs, e.g. the kidneys, spleen, and lymph nodes.
b The ligamentous sheath of connective tissue that surrounds various skeletal joints.