a- /ə,ä/ prefix
New English example: abroock /ə'brōōk,ä'brōōk/
Comes from Old English "on-" and later became "a-". Words that still use this prefix include: anew, awake, again, about, around, etc. The prefix replaces "re-", the Latin-rooted equivalent, which is used to describe something being performed again.