The Collaborative International Dictionary of English v.0.48:

Ho \Ho\, pron.
   Who. [Obs.]

   Note: In some Chaucer MSS. Ho

The Collaborative International Dictionary of English v.0.48:

Ho \Ho\, Hoa \Hoa\, n. [See Ho, interj., 2.]
   A stop; a halt; a moderation of pace.
   [1913 Webster]

         There is no ho with them.                --Decker.

The Collaborative International Dictionary of English v.0.48:

Ho \Ho\, prop. n. (Chem.)
   The chemical symbol for Holmium.
   [PJC] Ho

The Collaborative International Dictionary of English v.0.48:

Ho \Ho\, Hoa \Hoa\ (h[=o]), interj. [Cf. F. & G. ho.]
   1. Halloo! attend! -- a call to excite attention, or to give
      notice of approach. "What noise there, ho?" --Shak. "Ho!
      who's within?" --Shak.
      [1913 Webster]

   2. [Perhaps corrupted fr. hold; but cf. F. hau stop! and E.
      whoa.] Stop! stand still! hold! -- a word now used by
      teamsters, but formerly to order the cessation of
      anything. [Written also whoa, and, formerly, hoo.]
      [1913 Webster]

            The duke . . . pulled out his sword and cried "Hoo!"
                                                  --Chaucer.
      [1913 Webster]

            An herald on a scaffold made an hoo.  --Chaucer.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hydroxyl \Hy*drox"yl\, n. [Hydro-, 2 + oxygen + -yl.] (Chem.)
   A compound radical, or unsaturated group, HO, consisting of
   one atom of hydrogen and one of oxygen. It is a
   characteristic part of the hydrates, the alcohols, the oxygen
   acids, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ho
    n 1: a trivalent metallic element of the rare earth group;
         occurs together with yttrium; forms highly magnetic
         compounds [syn: holmium, Ho, atomic number 67]

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

handover
handoff
HO

    (HO, or "handoff") the mechanism by which an
   on-going cellular connection between a mobile terminal (MT,
   typically a mobile phone) or mobile host (MH) and a
   corresponding terminal or host is transferred from one point
   of access of the fixed network to another.

   Handover may occur because the phone is leaving its current
   cell, to balance demand between cells, to reduce interference
   or to transfer a user who has stopped moving to a nearby cell
   with shorter range.

   (2010-05-07)