English
above-board
From above + board (“table”).
first attested First attested in 1610 (as stated in the etymology)
The story
First attested in 1610. Said by Johnson to have been borrowed from gamblers, who, when they change their cards, put their hands under the table.
Today it means
adj In open sight; without trick, concealment, or deception.
Language periods are conventional ranges, not dates for this word.
Etymograph / above-board