Trine
In plain words
Two planets a third of the way round the circle from each other. They get on easily — so easily that the help is easy to miss and easy to waste.
In the tradition's terms
120° apart, in signs of the same element: the two natures run with the grain of each other.
In depth
Separation 120°. Same triplicity, so the flow needs no adjustment — which is precisely the classical caution: a trine gives, and gives whether or not you do anything with it.