The Collaborative International Dictionary of English v.0.48:

aegis \ae"gis\ ([=e]"j[i^]s), n. [L. aegis, fr. Gr. a'igi`s a
   goat skin, a shield, a'i`x goat, or fr. 'ai`:ssw to rush.]
   A shield or protective armor; -- applied in mythology to the
   shield of Jupiter which he gave to Minerva. Also fig.: A
   shield; a protection.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aegis
    n 1: kindly endorsement and guidance; "the tournament was held
         under the auspices of the city council" [syn: auspices,
         protection, aegis]
    2: armor plate that protects the chest; the front part of a
       cuirass [syn: breastplate, aegis, egis]

Moby Thesaurus II by Grady Ward, 1.0:

107 Moby Thesaurus words for "aegis":
   abetment, advocacy, arm guard, armament, armor, auspices, backing,
   backstop, bard, beaver, brassard, breastplate, buckler, buffer,
   bulletproof vest, bulwark, bumper, care, championship, charity,
   coif, contraceptive, copyright, corselet, countenance,
   crash helmet, cuirass, cushion, dashboard, dodger, encouragement,
   face mask, favor, fender, finger guard, foot guard, fosterage,
   fuse, gas mask, gauntlet, goggles, goodwill, governor, guard,
   guardrail, guidance, habergeon, hand guard, handrail, hard hat,
   hauberk, headpiece, helm, helmet, insulation, interest, interlock,
   jamb, knee guard, knuckle guard, laminated glass, life preserver,
   lifeline, lightning conductor, lightning rod, lorica, mail, mask,
   mudguard, nasal, nose guard, pad, padding, palladium, patent,
   patronage, pilot, plate, preventive, prophylactic, protection,
   protective clothing, protective umbrella, rondel, safeguard,
   safety, safety glass, safety plug, safety rail, safety shoes,
   safety switch, safety valve, screen, seat belt, seconding,
   security, shield, shin guard, sponsorship, sun helmet, sympathy,
   tutelage, umbrella, visor, ward, windscreen, windshield



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

AEGIS
       Advanced Electronic Guidance and Instrumentation System


The Free On-line Dictionary of Computing (30 December 2018):

AEGIS

    A Unix variant that was used on Apollo
   workstations before Apollo was bought by Hewlett Packard.
   AEGIS has some advantages over standard BSD or System V
   Unix.  It includes faster file access and a richer command
   set; there are commands to find out which process is running
   on a particular node, which process is locking a particular
   file, etc.

   (1997-02-25)


The Free On-line Dictionary of Computing (30 December 2018):

Aegis

    A CASE tool for project change
   management written by Peter Miller, with minor contributions
   by a few others.  Aegis is licensed using the GNU GPL but is
   not a GNU project.

   Aegis Home (http://aegis.sourceforge.net/).

   (2005-03-24)