I came across *akimbo* and *askance* today and wondered if they were related, with the opening 'a' signifying something. Apparently not:

> [Akimbo][1] - to stand with hands on hips and elbows out, from the C15
> *in kenebowe*, literally: in keen bow, that is, in a sharp curve.
> 
> 
> [Askance][2] - to look sideways, obliquely, especially with suspicion
> or doubt: origin obscure.

Other words take an 'a' prefix meaning a negative:

> [a- or an- \[Greek a- and an- un-, non-\]][3] Negative, not (abiotic,
> acaulescent, acephalia, aphasia, asexual, atrophy, anorexia).

But 'a' is also used as a prefix in words that are not negative, for example *his knees were all atremble.* What is the meaning of 'a' here? Could it have connections with akimbo and askance?

  [1]: http://www.thefreedictionary.com/akimbo
  [2]: http://www.thefreedictionary.com/askance
  [3]: http://www.macroevolution.net/biology-prefixes-a.html#.UW9FtWfyC1c