The Collaborative International Dictionary of English v.0.48:

Syn- \Syn-\ [Gr. sy`n with.]
   A prefix meaning with, along with, together, at the same
   time. Syn- becomes sym- before p, b, and m, and syl- before
   l.
   [1913 Webster] Synacme

The Collaborative International Dictionary of English v.0.48:

Trace \Trace\, n. [F. trace. See Trace, v. t. ]
   1. A mark left by anything passing; a track; a path; a
      course; a footprint; a vestige; as, the trace of a
      carriage or sled; the trace of a deer; a sinuous trace.
      --Milton.
      [1913 Webster]

   2. (Chem. & Min.) A very small quantity of an element or
      compound in a given substance, especially when so small
      that the amount is not quantitatively determined in an
      analysis; -- hence, in stating an analysis, often
      contracted to tr.
      [1913 Webster]

   3. A mark, impression, or visible appearance of anything left
      when the thing itself no longer exists; remains; token;
      vestige.
      [1913 Webster]

            The shady empire shall retain no trace
            Of war or blood, but in the sylvan chase. --Pope.
      [1913 Webster]

   4. (Descriptive Geom. & Persp.) The intersection of a plane
      of projection, or an original plane, with a coordinate
      plane.
      [1913 Webster]

   5. (Fort.) The ground plan of a work or works.
      [1913 Webster]

   Syn.-Vestige; mark; token. See Vestige.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Calumniate \Ca*lum"ni*ate\, v. i. [imp. & p. p. Calumniated;
   p. pr. & vb. n. calumniating.] [L. calumniatus, p. p. of
   calumniari. See Calumny, and cf. Challenge, v. t.]
   To accuse falsely and maliciously of a crime or offense, or
   of something disreputable; to slander; to libel.
   [1913 Webster]

         Hatred unto the truth did always falsely report and
         calumniate all godly men's doings.       --Strype.
   [1913 Webster]

   Syn. -- To asperse; slander; defame; vilify; traduce;
      belie; bespatter; blacken; libel. See Asperse.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Citadel \Cit"a*del\, n. [F. citadelle, It. citadella, di?. of
   citt? city, fr. L. civitas. See City.]
   A fortress in or near a fortified city, commanding the city
   and fortifications, and intended as a final point of defense.
   [1913 Webster]

   Syn. -- Stronghold. See Fortress.
      [1913 Webster]

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

SYN

   1.  Synchronous idle.

   2.  A syntactic specification language for COPS.

   ["Metalanguages of the Compiler Production System COPS",
   J. Borowiec, in GI Fachgesprach "Compiler-Compiler", ed
   W. Henhapl, Tech Hochs Darmstadt 1978, pp. 122-159].

   3. [TCP/IP SYN request?]

   (1996-04-17)