Pl. lacunæ, lacunas. [a. L. lacūna a hole, pit, f. lacus LAKE sb.4 Cf. LACUNE.]
1. In a manuscript, an inscription, the text of an author: A hiatus, blank, missing portion. Also transf.
1663. Sir R. Moray, in Lauderd. Papers (Camden), I. 181. You do well to leave no Lacunas in your letters.
1694. Gibson, in Lett. Lit. Men (Camden), 228. The lacuna of his behaviour in Holland, Dr. Gregory perhaps may be able to make up.
1851. D. Wilson, Preh. Ann., IV. v. (1863), II. 326. The context which fills up the numerous lacunae of the time-worn inscription.
1875. Maine, Hist. Inst., ix. 256. The description given … is followed by a lacuna in the manuscript.
1892. Zangwill, Bow Myst., 147. There were various lacunæ and hypotheses in the case for the defence.
2. Chiefly in physical science: A gap, an empty space, spot or cavity. a. gen.
1872. Proctor, Ess. Astron., xxiv. 303. The gaps and lacunae are left relatively clear of lucid stars.
1879. Rutley, Study Rocks, x. 107. Fluid lacunae … are of frequent occurrence in nepheline.
1880. Sat. Rev., 15 May, 637. The curious lacuna in the field of vision, known as the blind spot.
b. Anat. ‘A mucous follicle; also, a space in the connective tissue giving origin to a lymphatic’ (Syd. Soc. Lex., 1888).
1706. Phillips (ed. Kersey), Lacunæ are certain small Pores or Passages in the Neck of the Womb.
1722. Quincy, Lex. Physico-Med. (ed. 2), 175. Between this Muscle [Sphincter] and the inner membrane of the Vagina, there are several little Glands, whose excretory Ducts are called Lacunæ.
1874. Van Buren, Dis. Genit. Org., 77. Inflammation seals the orifice of the follicle and the lacuna is converted into a cyst containing pus.
c. Anat. One of the small cavities in the bone substance which contain the bone corpuscles or osteoblasts (Syd. Soc. Lex., 1888).
1845. Todd & Bowman, Phys. Anat., I. 109. They [pores] soon arrange themselves in sets, each of which … discharges itself into a small cavity or lacuna.
1859. [see LACUNAL a.].
1867. J. Hogg, Microsc., I. ii. 57. The observation of … the Haversian canals and the lacunæ of bones.
d. Zool. One of the spaces left among the tissues of the lower animals, which serve in place of vessels for the circulation of the body fluids.
1867. J. Hogg, Microsc., II. iii. 566. Minute capillary ramifications [in flukes] terminating in small oval shaped sacs or lacunæ.
e. Bot. An air-space in the cellular tissue of plants, an air-cell. Also, a small pit or depression on the upper surface of the thallus of lichens.
1836. Loudon, Encycl. Plants, 948. [Lichens] Lacunæ are small hollows or pits on the upper surface of the frond.
1856. in Henslow, Dict. Bot. Terms.
1874. Cooke, Fungi, 41. In Tuburcinia, the minute cells are compacted into a hollow sphere, having lacunæ communicating with the interior.
