abscess:

a localized accumulation of products of inflammation.

acanthella:

an acanthocephalan larval stage between an acanthor and a cystacanth.

acanthor:

the acanthocephalan larval stage that hatches from the egg.

acetabulum:

a sucker not surrounding a mouth.

acraspedote:

a cestode proglottid that does not overlap the one posterior to it.

allergic reaction:

secondary immune response to an environmental allergen.

adeagus:

chitinized spear-like structure in male Anoplura.

adult:

general term for a developmental stage capable of producing gametes.

ala:

lateral expansions of the cuticle of nematodes.

amastigote:

a form of Trypanosomatidae with a short flagellum.

amoeboid:

irregular and changeable in shape; movement by extension of pseudopodia.

apical complex:

a structure in merozoites and sporozites of Apicomplexa, comprising a polar ring, conoid, and rhoptries, that aids penetration of host cells.

amphistome:

a fluke with the ventral sucker located at the posterior end of the body.

anapolytic:

a cestode proglottid that does not detach from the strobila.

anchor:

any unusually large, hard, recurved structure used to aid attachment.

apolysis:

detachment of a tapeworm proglottid.

aporal:

located on the side of the body opposite to the genital pore.

appendix:

a blind-ending offshoot of the digestive tract.

armed:

possessing spines, hooks, or other hardened structures.

asexual:

a form of reproduction not involving the fusion of gametes

autoinfection:

for parasites that normally transmit from host to host by a free-living stage, the rapid development and establishement of a parasite in the same host individual from which it originated.

axostyle:

a tube-like organelle in some flagellate protozoans.