Definition of seat-of-the-pants in English:

seat-of-the-pants

adjective

informal
  • Of a person: tending to act instinctively, spontaneously, or expediently. Of an activity: done on the basis of practical experience rather than technical knowledge; informal; inexact.

Origin

1930s; earliest use found in Popular Science Monthly. From seat + of + the + pants, after by the seat of one's pants.

Pronunciation

seat-of-the-pants

/ˌsiːtə(v)ðəˈpants/