Kamae (構え?) is a Japanese term used in martial arts and traditional theater. It translates approximately to "posture". The Kanji of this word means "base".
Kamae is to be differentiated from the word tachi (立ち?), used in Japanese martial arts to mean stance. While tachi (pronounced dachi when used in a compound) refers to the position of the body from the waist down, kamae refers to the posture of the entire body, as well as encompassing one's mental posture (i.e., one's attitude). These connected mental and physical aspects of readiness may be referred to individually as kokoro-gamae (心構え?) and mi-gamae (身構え?), respectively.
Although it is a generic term, context may mean there's a default specific posture which is being implicitly referred to. e.g. many modern styles use kamae by itself as shorthand usually for the style's basic stance for sparring or self-defense.
As a further note, there are also related verbs, and adding te to the end of kamae makes the command for "get ready/in position" (構えて, kamaete?). Thus, a karate instructor ordering the students to assume a front stance might shout, "Zenkutsu dachi, kamaete!"