de·clen·sion /dɪˈklɛn(t)ʃən/
  詞尾變化,格變化,傾斜,衰退
  De·clen·sion n.
  1. The act or the state of declining; declination; descent; slope.
     The declension of the land from that place to the sea.   --T. Burnet.
  2. A falling off towards a worse state; a downward tendency; deterioration; decay; as, the declension of virtue, of science, of a state, etc.
  Seduced the pitch and height of all his thoughts
  To base declension.   --Shak.
  3. Act of courteously refusing; act of declining; a declinature; refusal; as, the declension of a nomination.
  4. Gram. (a) Inflection of nouns, adjectives, etc., according to the grammatical cases. (b) The form of the inflection of a word declined by cases; as, the first or the second declension of nouns, adjectives, etc. (c) Rehearsing a word as declined.
  Note: ☞ The nominative was held to be the primary and original form, and was likened to a perpendicular line; the variations, or oblique cases, were regarded as fallings (hence called casus, cases, or fallings) from the nominative or perpendicular; and an enumerating of the various forms, being a sort of progressive descent from the noun's upright form, was called a declension.
  Declension of the needle, declination of the needle.
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  declension
       n 1: the inflection of nouns and pronouns and adjectives in
            Indo-European languages
       2: process of changing to an inferior state [syn: deterioration,
           decline in quality, worsening]
       3: a downward slope or bend [syn: descent, declivity, fall,
           decline, declination, downslope] [ant: ascent]
       4: a class of nouns or pronouns or adjectives in Indo-European
          languages having the same (or very similar) inflectional
          forms; "the first declension in Latin"