Not Cilantro

Due to the influence of some eighteenth or nineteenth century English literature. This author has been pondering the significance of the most appropriate musical voice to accompany a soprano in a duet. The only problem  being my complete inability to remember the proper term.  
It is not cilantro, as my botanical brain helpfully supplied. 
It was not clarinet, though that was a more musical term.

The term would briefly pop into my head with a flash of insight and then be gone in a moment. 

Why does the brain do this to us? 

Contralto! 

*sighs*

​Perhaps it will last this time.