A situational joseki is a sequence of moves that doesn't give a locally even result, but may be regarded as standard play in certain types of whole board position. The term was used (but not defined) by Rui Naiwei in her book Essential Joseki.
In the 4-5 point 4-3 approach inside contact joseki, the second player will normally respond to the contact play with a hane. But tenuki is also possible, taking a loss in the corner in exchange for influence elsewhere.
Rui Naiwei refers to this sequence as a situational joseki. The normal move would be at a. In this diagram, works well with the circled stones below.
N. B. The sequence, - , appears as joseki in the Kitani-Suzuki "Small Joseki Dictionary". Today's bots often prefer at a. Also, tenuki after may be played on the theory that White has prevented Black from making an ideal enclosure with sente.
In the 3-4 point low approach three-space low pincer joseki, when white jumps out, black will normally defend the corner. But Rui Naiwei gives this alternative as situational joseki: