pronunciation - Different prononunciations of "consummate"

How can one remember the pronunciations of consummate, which depend on its state as a verb or adjective?

I venture that because its verbal definition involves intercourse, thus the "mate" rhymes with the single noun mate. But is this right?

Moreover, what's the rationale or reasoning behind the differences?

Answer

Whenever the stress in such -ate words is not on the final syllable, then generally the last syllable will be:

• 
  

  for verbs: /eɪt/ [long vowel]

  
  


• 
  

  for adjectives: /ət/ [short schwa vowel]

  
  

The speaker may use a glottal stop in either case as an allophone of the /t/.

When the word stress does fall on the final syllable, however, the word will end in /eɪt/ regardless, even if it is an adjective:

• irate /aɪˈreɪt/

If the word is a verb, then usually the suffix -tion can be used to convert it into a noun. You will note in this case that the /eɪ/ sound will not change, as it will be full length in this position. This is because it will take the main stress in the word. The -tion suffix actually requires the preceding syllable to be stressed.

In other words if the word is a verb it should have the same vowel sound as the -tion noun. It's not really a case of a rationale, though. It's more just how the language has evolved - not how it's been designed!