Old English seofon, from Proto-Germanic *sebun (cf. Old Saxon sibun, Old Norse sjau, Swedish sju, Danish syv, Old Frisian sowen, siugun, Middle Dutch seven, Dutch zeven, Old High German sibun, German sieben, Gothic sibun), from PIE *septm "seven" (cf. Sanskrit sapta, Avestan hapta, Hittite shipta, Greek hepta, Latin septem, Old Church Slavonic sedmi, Lithuanian septyni, Old Irish secht, Welsh saith).
Long regarded as a number of perfection (e.g. seven wonders; seven sleepers, the latter translating Latin septem dormientes; seven against Thebes, etc.), but that notion is late in Old English and in German a nasty, troublesome woman could be eine böse Sieben "an evil seven" (1662).
Magical power or healing skill associated since 16c. with the seventh son ["The seuenth Male Chyld by iust order (neuer a Gyrle or Wench being borne betweene)," Thomas Lupton, "A Thousand Notable Things," 1579]. The typical number for "very great, strong," e.g. seven-league boots in the fairy story of Hop o'my Thumb. The Seven Years' War (1756-63) is also the Third Silesian War.
The Seven Stars (Old English sibunsterri), usually refers to the Pleiades, though in 15c. and after this name occasionally was given to the Big Dipper (which also has seven stars), or the seven planets of classical astronomy. Popular as a tavern sign, it might also (with six in a circle, one in the center) be a Masonic symbol.
FOOL: ... The reason why the
seven stars are no more than seven is a pretty reason.
LEAR: Because they are not eight?
FOOL: Yes, indeed: thou wouldst make a good fool.
["King Lear," Act I, Scene V]
This number occurs frequently in Scripture, and in such connections as lead to the supposition that it has some typical meaning. On the seventh day God rested, and hallowed it (Gen. 2:2, 3). The division of time into weeks of seven days each accounts for many instances of the occurrence of this number. This number has been called the symbol of perfection, and also the symbol of rest. "Jacob's seven years' service to Laban; Pharaoh's seven fat oxen and seven lean ones; the seven branches of the golden candlestick; the seven trumpets and the seven priests who sounded them; the seven days' siege of Jericho; the seven churches, seven spirits, seven stars, seven seals, seven vials, and many others, sufficiently prove the importance of this sacred number" (see Lev. 25:4; 1 Sam. 2:5; Ps. 12:6; 79:12; Prov. 26:16; Isa. 4:1; Matt. 18:21, 22; Luke 17:4). The feast of Passover (Ex. 12:15, 16), the feast of Weeks (Deut. 16:9), of Tabernacles (13:15), and the Jubilee (Lev. 25:8), were all ordered by seven. Seven is the number of sacrifice (2 Chr. 29:21; Job 42:8), of purification and consecration (Lev. 42:6, 17; 8:11, 33; 14:9, 51), of forgiveness (Matt. 18:21, 22; Luke 17:4), of reward (Deut. 28:7; 1 Sam. 2:5), and of punishment (Lev. 26:21, 24, 28; Deut. 28:25). It is used for any round number in such passages as Job 5:19; Prov. 26:16, 25; Isa. 4:1; Matt. 12:45. It is used also to mean "abundantly" (Gen. 4:15, 24; Lev. 26:24; Ps. 79:12).