Antonym for ameliorate

I have been searching online for a particular word; that approximates to an antonym of ameliorate. I am after a specific word.

ameliorate verb

to make better
Synonyms ameliorate, amend, better, enhance, enrich, help, meliorate, perfect, refine, upgrade
Related Words correct, emend, rectify, reform, remediate, remedy; edit, fine-tune, redraft, refurbish, rehab, rehabilitate, revamp, revise, rework; beef (up), boost, fortify, intensify, reinforce (also reenforce), strengthen; fine, hone, polish; retouch, touch up
Near Antonyms damage, endamage, harm, hurt, impair, injure, spoil, tarnish, vitiate; blemish, blight, deface, disfigure, flaw, mar; diminish, lessen, lower, reduce
Antonyms worsen

The word is eluding me... it sounds like detiliorate.. not deteriorate. My example is, probably, misleading, as my searches on google are not throwing up any alternative words.. So I'm probably way off base.

Anyone know the word I am trying to remember?

exacerbate

From WordNet (r) 3.0 (2006) [wn]:

  exacerbate
      v 1: make worse; "This drug aggravates the pain" [syn: {worsen},
           {aggravate}, {exacerbate}, {exasperate}] [ant:
           {ameliorate}, {amend}, {better}, {improve}, {meliorate}]
      2: exasperate or irritate [syn: {exacerbate}, {exasperate},
         {aggravate}]

I don't think there is an antonym that ends with an -iorate because the words ameliorate and meliorate derive from a single stem (see below). The closest etymological antonym is aggravate

ameliorate comes from French meilleur and ameliorer - the direct French antonym for this word is aggraver meaning 'to make worse'.