계시다
gyesida · TOPIK 1
to be, to stay (honorific)
계시다 = honorific 있다: gye-shi-da, the guest she (shi) is staying
The plain verb 있다 (to be, to stay) swaps to 계시다 when the subject deserves respect, like a grandparent or teacher. The 시 inside matches the honorific marker -시- found in other respectful verbs, a handy verbal flag for politeness.