A major seventh chord is composed using a root/1st, major 3rd, perfect 5th and major 7th (or R/1-3-5-7) intervals played simultaneously. Generally written as CMA7, Cma7 or CΔ7, it is good practice to simply use an uppercase C with the uppercase letters MA followed by a super scripted 7 to represent it in writing (ie: CMA7).
The tonality of a major seventh chord is consonant, resolved and stable, it does not "lead away" from itself like the dominant seventh chord, or leave the listener with a sense of "suspense" like the minor seventh flat five chord.
Major seventh chord profile
|Intervals||root/1st, major 3rd, perfect 5th, major 7th or R/1-3-5-7|
|Stability||Consonant, stable, resolved|
|Common names (examples in C)||CMA7, Cmaj7, CMAJ7, Cma7, CΔ7|
Major seventh chord table
|Chord name||Root||Major third||Perfect fifth||Major seventh|
|C♯MA7||C♯||E♯ (F)||G♯||B♯ (C)|
|D♯MA7||D♯||F (G)||A♯||C (D)|
|G♯MA7||G♯||B♯ (C)||D♯||F (G)|
|A♯MA7||A♯||C (D)||E♯ (F)||G (A)|
|D Major chord voicing #1|