dandha : [adj.] slow; silly; stupid.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

Dandha (adj.) [Sk.? Fausböll refers it to Sk. tandra; Trenckner (Notes 65) to dṛḍha; see also Müller, P. Gr. 22, & Lüders Z.D.M.G. 58, 700. A problematic connection is that with thaddha & datta2 (q. v.)] slow; slothful, indocile; silly, stupid M i.453; S iv.190; Dh 116; J i.116, 143; ii.447; v.158; vi.192 (+laḷāka); Th 1, 293; Miln 59, 102, 251; DhA i.94, 251; iii.4. Vism 105, 257 (with ref. to the liver).
   -- âbhiññā sluggish intuition D iii.106; A v.63; Dhs 176; Nett 7, 24, 50, 123 sq., cp. A ii.149 sq.; Vism 85.

Pali-English Dictionary, TW Rhys Davids, William Stede,