The Collaborative International Dictionary of English v.0.48:

Bathos \Ba"thos\ (b[=a]"th[o^]s), n. [Gr. ba`qos depth, fr.
   baqy`s deep.] (Rhet.)
   A ludicrous descent from the elevated to the low, in writing
   or speech; anticlimax.
   [1913 Webster] bath towel

WordNet (r) 3.0 (2006):

bathos
    n 1: triteness or triviality of style
    2: insincere pathos [syn: mawkishness, bathos]
    3: a change from a serious subject to a disappointing one [syn:
       anticlimax, bathos]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "bathos":
   anticlimax, bleeding heart, cloyingness, comedown, goo,
   hearts-and-flowers, heaviness, heaviness of heart, heavy heart,
   heavyheartedness, maudlinness, mawkishness, mush, mushiness,
   namby-pamby, namby-pambyism, namby-pambyness, nostalgia,
   nostomania, oversentimentalism, oversentimentality, pathos,
   romanticism, sadheartedness, sadness, sentiment, sentimentalism,
   sentimentality, slop, sloppiness, slush, soap opera, sob story,
   sweetness and light, tearjerker