Cautionary \Cau"tion*a*ry\, a.

1. Conveying a caution, or warning to avoid danger; as, cautionary signals.

2. Given as a pledge or as security.

He hated Barnevelt, for his getting the cautionary towns out of his hands. --Bp. Burnet.

3. Wary; cautious. [Obs.]

--Bacon.

Source: Webster's Revised Unabridged Dictionary (1913)