【Adorn】 , 【decorate】 , 【ornament】 , 【embellish】 , 【beautify】 , 【deck】 , 【bedeck】 and 【garnish】 all mean to add something unessential in order to enhance the appearance.

These words and especially the first five are often used interchangeably; certain distinctions, however, are apparent in precise use especially when the subject of the verb is the thing that enhances rather than the agent or enhancer.

An element that adorns not only serves to heighten the beauty of its background or setting but also is beautiful in itself.

• few nobler poems have adorned our time
  —Quiller-Couch
• the simplicity with which great composers 【adorn】 their works
  —Braithwaite

One that decorates relieves the plainness or monotony of a background by contributing beauty of color or design to it.

• the walls are yet to be decorated
• the use of inlaying in decorating furniture

Something ornaments when it is an adjunct or an accessory which sets off a thing to advantage.

• whose bridle was ornamented with silver bells
  —Scott
• a doorway ornamented with pillars

【Embellish】 more often suggests the act of an agent than the effect of a thing. One who embellishes modifies his material, especially by adding adventitious or sometimes gaudy or fictitious 【ornament】 for the sake of effect.

• embellishes his style with imagery
• feats of virtuosity . . . with which she embellished the usual routine of the role
  —Sargeant

【Embellish】 often suggests disregard for truth.

• that theme is then expertly embellished by the Communists to prove that Wall Street is on the warpath against the Kremlin
  —Fischer

One that beautifies either enhances the beauty of something or counterbalances its plainness or ugliness.

• an embankment swathed and beautified by clambering roses
• the eternal orbs that 【beautify】 the night
  —Shelley

One that decks or bedecks contributes to the gaiety, splendor, or, especially in the case of 【bedeck】 , showiness of appearance

• 【bedeck】 oneself with jewels
• decking with liquid pearl the bladed grass
  —Shak.
• he likes to 【deck】 out his little person in splendor and fine colors
  —Thackeray

One garnishes something when one gives it the final touch of order or 【ornament】 in preparation for use or service.

• the drawing room was empty, swept and garnished, waiting for the next bout
  —Panter-Downes

The word is used especially in cookery.

• 【garnish】 a broiled fish with lemon slices and chopped parsley