sīnus (noun M) : v. sinum.

sĭnus (noun M) :
* In gen., a bent surface (raised or depressed), a curve, fold, a hollow, etc. (so mostly poet. and in postAug. prose): draco ... conficiens sinus e corpore flexos, folds, coils, Cic. poët. N. D. 2, 42, 106; so Ov. M. 15, 689; 15, 721: sinu ex togā facto,Liv. 21, 18 fin.—Of the bag of a fishing-net: quando abiit rete pessum, tum adducit sinum (piscator),Plaut. Truc. 1, 1, 15; so Juv. 4, 41; and of a hunter's net,Mart. 13, 100; Grat. Cyn. 29; also of a spider's web,Plin. 11, 24, 28, § 82.—Of the bend or belly of a sail swollen by the wind: velorum plenos subtrahis ipse sinus,Prop. 3, 9 (4, 8), 30; and so with or without velum,Tib. 1, 3, 38; Verg. A. 3, 455; 5, 831; Ov. A. A. 3, 500; Luc. 6, 472; Sil. 7, 242; Quint. 10, 7, 23; 12, 10, 37 al.—Of hair, a curl, ringlet: ut fieret torto flexilis orbe sinus,Ov. Am. 1, 14, 26; id. A. A. 3, 148.— Of the curve of a reaping-hook: falcis ea pars, quae flectitur, sinus nominatur,Col. 4, 25, 1 sq.—Of bones, a sinus: umeri,Cels. 8, 1 med.; cf. ulceris,id. 7, 2 med.: suppurationis ferro recisae,Col. 6, 11, 1; Veg. 4, 9, 3.
* In partic.
* The hanging fold of the upper part of the toga, about the breast, the bosom of a garment; also the bosom of a person; sometimes also the lap (= gremium, the predom. class. signif.; esp. freq. in a trop. sense).
* Lit.: est aliquid in amictu: quod ipsum aliquatenus temporum condicione mutatum est. Nam veteribus nulli sinus, perquam breves post illos fuerunt,Quint. 11, 3, 137; cf. decentissimus,id. 11, 3, 140 sq.: (Caesar moriens) sinistrā manu sinum ad ima crura deduxit, quo honestius caderet,Suet. Caes. 82 (for which, of the same: togam manu demisit,Val. Max. 4, 5, 6); Tib. 1, 6, 18: praetextae sinus,Suet. Vesp. 5: ne admissum quidem quemquam senatorum nisi solum et praetentato sinu,id. Aug. 35: ut conchas legerent galeasque et sinus replerent,id. Calig. 46: cedo mihi ex ipsius sinu litteras Syracusanorum,Cic. Verr. 2, 5, 57, § 147: aurum in sinu ejus invenerunt,Quint. 7, 1, 30: paternos In sinu ferens deos,Hor. C. 2, 18, 27: nuda genu, nodoque sinus collecta fluentis,Verg. A. 1, 320: et fluit effuso cui toga laxa sinu,Tib. 1, 6, 14; cf.: micat igneus ostro, Undantemque sinum nodis irrugat Iberis,Stat. Th. 4, 265: ad haec, quae a fortunā sparguntur, sinum expandit,eagerly embraces, grasps,Sen. Ep. 74, 6: aliquid velut magnum bonum intra sinum continere,id. Vit. Beat. 23, 3; cf.: sinum subducere alicui rei,to reject,id. Thyest. 430.—Prov.: sinu laxo (i. e. soluto) ferre aliquid,i. e. to be careless about a thing,Hor. S. 2, 3, 172.
* A bay, bight, gulf: ut primum ex alto sinus ab litore ad urbem inflectitur,Cic. Verr. 2, 5, 12, § 30; cf.: portus infusi in sinus oppidi,id. Rep. 3, 31, 43; 1, 3, 5; id. Imp. Pomp. 11, 31; Cic. Verr. 2, 5, 56, § 145; id. Att. 16, 6, 1; * Caes. B. C. 2, 32; Sall. J. 78, 2; Liv. 8, 24; Plin. 2, 43, 44, § 114 (Jahn, nivibus); Suet. Aug. 98; id. Tib. 16; Verg. A. 1, 243; 6, 132; Hor. C. 1, 33, 16; id. Epod. 10, 19.
* Trop.
* Poet., a garment, in gen.: Tyrio prodeat apta sinu,Tib. 1, 9, 72; 1, 6, 18: auratus,Ov. F. 2, 310: purpureus,id. ib. 5, 28: regalis,id. H. 13, 36; 5, 71; Stat. S. 2, 1, 133.
* The bosom of a person: manum in sinum alicui Inserere,Ter. Heaut. 3, 3, 2: gelu rigentem colubram sinu fovit,Phaedr. 4, 17, 3: opposuit sinum Antonius stricto ferro,Tac. H. 3, 10: scortum in sinu consulis recubans,Liv. 39, 43: tangitur, et tacto concipit illa sinu, i. e. utero,Ov. F. 5, 256: usque metu micuere sinus, dum, etc.,id. H. 1, 45: horum in sinum omnia congerebant,Plin. Pan. 45.
* The bosom, as in most other languages, for love, protection, asylum, etc. (usu. in the phrases in sinu esse, habere, etc.; syn. gremium): hic non amandus? hiccine non gestandus in sinu est?Ter. Ad. 4, 5, 75: iste vero sit in sinu semper et complexu meo,Cic. Fam. 14, 4, 3; cf.: postremum genus proprium est Catilinae, de ejus delectu, immo vero de complexu ejus ac sinu,id. Cat. 2, 10, 22: suo sinu complexuque aliquem recipere,id. Phil. 13, 4, 9; so (with complexus) id. ib. 2, 25, 61: (Pompeius), mihi crede, in sinu est,is very dear to me,id. Q. Fr. 2, 13, 1: Bibulum noli dimittere e sinu tuo,from your intimacy,id. ad Brut. 1, 7, 2: praesertim si in amici sinu defieas,on the bosom,Plin. Ep. 8, 16, 5: in hujus sinu indulgentiāque educatus,Tac. Agr. 4; so id. Or. 28; cf.: etsi commotus ingenio, simulationum tamen falsa in sinu avi perdidicerat, i. e. under the care or tuition, id. A. 6, 45 fin.: confugit in sinum tuum concussa respublica,i. e. into your arms,Plin. Pan. 6, 3; id. Ep. 8, 12, 1: optatum negotium sibi in sinum delatum esse dicebat,committed to his guardianship, care,Cic. Verr. 2, 1, 50, § 131; cf. Plin. Pan. 45, 2: respublica in Vespasiani sinum cessisset,Tac. H. 3, 69; 3, 19; Dig. 22, 3, 27: sinum praebere tam alte cadenti,protection,Sen. Ira, 3, 23, 6.
* The interior, the inmost part of a thing: alii intra moenia atque in sinu urbis sunt hostes,in the midst, in the heart of the city,Sall. C. 52, 35: in urbe ac sinu cavendum hostem,Tac. H. 3, 38; Sil. 4, 34; 6, 652; Claud. Eutr. 2, 575: ut (hostis) fronte simul et sinu exciperetur,in the centre,Tac. A. 13, 40: in intimo sinu pacis,i. e. in the midst of a profound peace,Plin. Pan. 56, 4.
* In sinu alicujus, in the power or possession of (postAug. and rare): opes Cremonensium in sinu praefectorum fore,Tac. H. 3, 19: omnem fortunam in sinu meo habui,Dig. 22, 3, 27.
* A hiding-place, place of concealment: ut in sinu gaudeant, gloriose loqui desinunt, qs. in their bosoms (or, as we say, in their sleeve), i. e. in secret, Cic. Tusc. 3, 21, 51; so of secret joy,Tib. 4, 13, 8: in tacito cohibe gaudia clausa sinu,Prop. 2, 25 (3, 20), 30; Sen. Ep. 105, 3; cf. also: plaudere in sinum,Tert. Pudic. 6: suum potius cubiculum ac sinum offerre contegendis quae, etc., the secrecy or concealment of her bed-chamber, Tac. A. 13, 13: abditis pecuniis per occultos aut ambitiosos sinus,i. e. in hidingplaces offered by obscurity or by high rank,id. H. 2, 92.
* Sinus Abrahae, the place of the spirits of the just (eccl. Lat.): sinum Abrahae, regionem non caelestem, sublimiorem tamen Inferis,Tert. adv. Marc. 4, 34.
* Transf.
* The land lying on a gulf, a point of land that helps to form it (perh. not ante-Aug.): segetibus in sinu Aenianum vastatis,Liv. 28, 5 Drak.: jam in sinum Maliacum venerat (with an army),id. 37, 6; Tac. A. 14, 9; id. H. 3, 66; id. Agr. 23; Plin. 6, 8, 8, § 23; Just. 2, 4, 26; 24, 4, 3.
* A curve or fold in land, a basin, hollow, valley: Arpini terra campestri agro in ingentem sinum consedit,Liv. 30, 2, 12: subito dehiscit terra, et immenso sinu laxata patuit,Sen. Oedip. 582; id. Herc. Fur. 679; Plin. 2, 44, 44, § 115: jugum montis velut sinu quodam flexuque curvatum,Curt. 3, 4, 6: montium,id. 3, 9, 12.