an(a)-

Variously up, back, or again.

Greek ana, up, back, again, anew.

Some common words show the variety of senses of the Greek original: an anagram, a word or phrase formed by rearranging the letters of another, comes from Greek ana‑ in the sense of ‘anew’, plus gramma, a letter; anatomy, the study of bodily structure, is literally ‘cutting up’ (from tomia, a cutting) because dissection is an essential part of that study; an anachronism, a thing belonging or appropriate to a period other than that in which it exists, comes from ana‑ in the sense of ‘backwards’, plus khronos, time.

Most words containing this form are technical terms in the arts and sciences. Some examples are anabolic (Greek ballein, to throw), of the metabolic synthesis of molecules in living organisms; anadromous (Greek dromos, running), of a fish, such as the salmon, that migrates up rivers from the sea to spawn; anode (Greek hodos, way), the positively charged electrode by which the electrons leave an electrical device; anaphylactic (Greek phulaxis, guarding), of an extreme allergic reaction, for example to a bee sting.