- ascusA sac-shaped cell present in ascomycete fungi; it is a reproductive cell in which meiosis and an additional cell division produce eight spores.
- asconA cavity, in the form of a bag or tube, lined with choanocytes, that forms the structure of sponges
- ascococcusA form of micrococcus, found in putrid meat infusions, occurring in peculiar masses, each of which is enclosed in a hyaline capsule and contains a large number of spherical micrococci.
- askosAn Ancient Greek pottery vessel used to pour small quantities of liquids such as oil.