Plain English Meaning
The two little house-shaped markings on the turn indicator. When the turn needle points at one of them, you are turning at the standard rate of 3 degrees per second, which completes a full 360° turn in two minutes.
Full Definition
The two reference indices on the face of a turn-and-slip indicator, positioned on either side of the center mark, that the turn needle aligns with to indicate a standard-rate turn (3° per second). Their outline — a small rectangle topped with a peaked roof — resembles a child's drawing of a doghouse, giving them their informal name.
Context Anchor
Seen on the turn-and-slip indicator during instrument flying, especially when holding a steady or turn by reference to instruments.