The Collaborative International Dictionary of English v.0.48:

Ken \Ken\, v. i.
   To look around. [Obs.] --Burton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ken \Ken\, n.
   Cognizance; view; especially, reach of sight or knowledge.
   "Beyond his ken." --Longfellow.
   [1913 Webster]

         Above the reach and ken of a mortal apprehension.
                                                  --South.
   [1913 Webster]

         It was relief to quit the ken
         And the inquiring looks of men.          --Trench.
   Kendal green

The Collaborative International Dictionary of English v.0.48:

Ken \Ken\ (k[e^]n), n. [Perh. from kennel.]
   A house; esp., one which is a resort for thieves. [Slang,
   Eng.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ken \Ken\, v. t. [imp. & p. p. Kenned (k[e^]nd); p. pr. & vb.
   n. Kenning.] [OE. kennen to teach, make known, know, AS.
   cennan to make known, proclaim, or rather from the related
   Icel. kenna to know; akin to D. & G. kennen to know, Goth.
   kannjan to make known; orig., a causative corresponding to
   AS. cunnan to know, Goth. kunnan. [root]45. See Can to be
   able, Know.]
   1. To know; to understand; to take cognizance of. [Archaic or
      Scot.]
      [1913 Webster]

   2. To recognize; to descry; to discern. [Archaic or Scot.]
      "We ken them from afar." --Addison
      [1913 Webster]

            'T is he. I ken the manner of his gait. --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ken
    n 1: range of what one can know or understand; "beyond my ken"
         [syn: cognizance, ken]
    2: the range of vision; "out of sight of land" [syn: sight,
       ken]

Moby Thesaurus II by Grady Ward, 1.0:

155 Moby Thesaurus words for "ken":
   absorb, acquaintance, appreciate, apprehend, assimilate,
   be acquainted with, be apprised of, be aware of, be cognizant of,
   be conscious of, be conversant with, be informed, be with one,
   behold, catch, catch on, catch sight of, clap eyes on, clear sight,
   cognize, color vision, command, comprehend, comprehension,
   conceive, conceptualize, cone vision, corpus, data, datum,
   day vision, daylight vision, descry, dig, digest, discern,
   discernment, discover, distinguish, domination, espy, experience,
   expertise, eye, eye-mindedness, eyereach, eyeshot, eyesight, facts,
   factual base, familiarity, farsight, farsightedness, fathom,
   field of view, field of vision, follow, get, get hold of,
   get the drift, get the idea, get the picture, glimpse, grasp, have,
   have in sight, have information about, have it taped,
   have knowledge of, horizon, information, intelligence, intimacy,
   keen sight, know, know-how, knowing, knowledge, lay eyes on, learn,
   limit of vision, line of sight, look on, look upon, make out,
   master, naked eye, night vision, notice, observe, outlook,
   outlook over, perceive, perception, peripheral field,
   peripheral vision, perspective, perspicacity, perspicuity,
   photopia, pick out, possess, power of sight, practical knowledge,
   prehend, private knowledge, privity, prospect, purview,
   quick sight, range, ratio cognoscendi, reach, read, realize,
   recognize, rod vision, savvy, scan, scope, scope of vision,
   scotopia, see, seeing, seize, seize the meaning, self-knowledge,
   sense, sense of sight, sight, sightedness, sightliness, spot, spy,
   survey, sweep, take, take in, technic, technics, technique, twig,
   twilight vision, understand, understanding, unobstructed vision,
   view, vision, vista, visual acuity, visual field, visual sense,
   witness, wot, wot of



The Jargon File (version 4.4.7, 29 Dec 2003):

ken
 /ken/, n.

    1. [Unix] Ken Thompson, principal inventor of Unix. In the early days he
    used to hand-cut distribution tapes, often with a note that read ?Love, ken
    ?. Old-timers still use his first name (sometimes uncapitalized, because
    it's a login name and mail address) in third-person reference; it is widely
    understood (on Usenet, in particular) that without a last name ?Ken? refers
    only to Ken Thompson. Similarly, ?Dennis? without last name means Dennis
    Ritchie (and he is often known as dmr). See also demigod, Unix.

    2. A flaming user. This was originated by the Software Support group at
    Symbolics because the two greatest flamers in the user community were both
    named Ken.


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

ken

   /ken/ 1. Ken Thompson

   2. A flaming user.  This was originated by the Software
   Support group at Symbolics because the two greatest flamers
   in the user community were both named Ken.

   [Jargon File]