āḷaka

(or f.)

  1. a thorn, sting, dart, spike used either as arrow-straightener Mil.418; Dhp-a.i.288 or (perhaps also for piece of bone, fishbone) in making up a comb Vv-a.349 (˚sandhāpana = comb; how Hardy got the meaning of “alum” in Ind. to Vv-a is incomprehensible).
  2. a peg, spike, stake or post (to tie an elephant to, cp. ālāna). Cp.ii.1#3. Alamba = alambara

Dimin of aḷa (?) or of ārā i.(?). See Morris J.P.T.S. 1886, 158