"seven" in Webster's Dictionary

seven adj. totaling one more than six. n. 1. the cardinal number between six and eight 7; VII. 2. a person or thing numbered seven, as a  contestant, a playing card etc.

Seven against Thebes

seven deadly sins 

Seven hills of Rome

seven seas

seventh  adj .... 3 in music, a) a note seven degrees above or below another in the diatonic scale; b) the interval between  these c) the seventh note of  the diatonic scale; leading note; subtonic. d) the chord formed by any tone and the third, fifth, and seventh of which it is the fundamental: also seventh chord.

seventh-day, adj. 1. of the seventh day (Saturday) 2. [often S- ]. observing the Sabbath on Saturday: as, Seventh day Adventists.

seventh heaven, 1. the seventh, usually highest, of the concentric spheres in which the stars are supposed to be fixed, according to various ancient systems of astronomy, or in whieh God and his angels are, according to certain theologies hence, 2. a condition of perfect happiness.

seven-up  n. a card game for two, three, or four persons in which seven points constitute a game.

Seven Wonders of the World

Seven Years' War, l756-l763; a war in which England and Prussia defeated Austria, France, Russia, Sweden. and Saxony.