The Asa is the collective noun given to the Norse pantheon and includes both the Aesir and the Vanir; the Asa are not merely synonymous with the Aesir. Moreover, the term Asa frequently has a much more religious connotation than the simple terms Aesir and Vanir, indicative of worship: it is the root of the contemporary re-implementation of pre-Christian Norse beliefs, Asatru. The membership of the gods to the Asa is often referred to directly within the Edda as e.g. Asa-Thor or Asa-Loki.
Asa was a Hebrew King in the Old Testament. (stub: more soon)
Also the former wiki name of the Wikipedian Asa Winstanley.