a. [f. prec. + -AL 1.] Of the nature of, or pertaining to, the arachnoid. Arachnoideal, -ean, -eous a. unnecessary variants of ARACHNOID, -AL.
1855. Ramsbotham, Obstet. Med., 64. An extremely delicate arachnoidal membrane.
1874. Jones & Siev., Pathol. Anat., 235. Arachnoidal effusion … speedily proves fatal.
1842. E. Wilson, Anat. Vade M., 373. The arachnoid is attached to the pia mater of the brain by a loose cellular tissue, the sub-arachnoidean.
1851. Crabb, Arachnoideous in Bot.
1877. Burnett, Ear, 89. This space marks an extension of the arachnoideal sac of the brain running along the facial nerve.
