'Sessile' definitions:

Definition of 'sessile'

From: WordNet
adjective
Permanently attached to a substrate; not free to move about; "sessile marine animals and plants" [ant: vagile]
adjective
Attached directly by the base; not having an intervening stalk; "sessile flowers"; "the shell of a sessile barnacle is attached directly to a substrate" [syn: sessile, stalkless] [ant: pedunculate, stalked]

Definition of 'Sessile'

From: GCIDE
  • Sessile \Ses"sile\, a. [L. sessilis low, dwarf, from sedere, sessum, to sit: cf. F. sessile.]
  • 1. Attached without any sensible projecting support. [1913 Webster]
  • 2. (Bot.) Resting directly upon the main stem or branch, without a petiole or footstalk; as, a sessile leaf or blossom. [1913 Webster]
  • 3. (Zool.) Permanently attached; -- said of the gonophores of certain hydroids which never became detached. [1913 Webster]