Actually, the definition has nothing to do with TM law. The correct answer is there is a registered TM for prime rate in the field of hotel reservations. Though generic in nature, if the OP used the domain in this field, there could be a challenge.
So, using he logic from spikodo, windows is not a TM either, right???? Here is the definition I found...
win·dow ( P ) Pronunciation Key (wnd)
n.
An opening constructed in a wall or roof that functions to admit light or air to an enclosure and is often framed and spanned with glass mounted to permit opening and closing.
A framework enclosing a pane of glass for such an opening; a sash.
A pane of glass or similar material enclosed in such a framework.
An opening that resembles a window in function or appearance.
The transparent panel on a window envelope.
The area or space immediately behind a window, especially at the front of a shop.
A means of access or observation: St. Petersburg was Peter the Great's window onto the Baltic.
An interval of time during which an activity can or must take place: a brief window of opportunity for a space mission; a window of vulnerability during which the air force was subject to attack.
Strips of foil dropped from an aircraft to confuse enemy radar; chaff.
A range of electromagnetic frequencies that pass unobstructed through a planetary atmosphere.
Computer Science. A rectangular area on the screen that displays its own file or message independently of the other areas of the screen.
Aerospace.
A launch window.
An area at the outer limits of the earth's atmosphere through which a spacecraft must pass in order to return safely.
