aboveboard

Concise Oxford English Dictionary © 2008 Oxford University Press:
above/əˈbʌv/

▶preposition & adverb

• 1 at a higher level or rank than.

  ■ higher than a particular amount or rate.

• 2 in preference to.

• 3 [as adv.] (in printed text) mentioned earlier.

– phrases
above all (else) more so than anything else.
above board legitimate and honest.
above oneself conceited.
not be above be capable of stooping to (an unworthy act).

– origin OE abufan, from a- ‘on’ + bufan (from bi ‘by’ + ufan ‘above’).