Well, a dry drunk is a person who has quit drinking but still has the dysfunctional behaviors/thoughts of an active alcoholic. Dry drunks basically don't have the general happiness/motivation/spiritual connection/meaningful life that sober/recovered/non-addicted people have. Their communication styles/world views/self esteem are all lacking--still primarily negative, self-centered, closed off, unhappy. In other words, they don't embrace their lives or relationships with openness, optimism, or motivation. They're dry, but not recovered. They are still wrapped up in their anxities and not living life very well.
Which came first, the alcoholism or the miserable human being? Is a dry drunk fundamentally a jerk or a neurotic, or emotionally/spiritually undeveloped and stagnant from years of addictive thinking and its attendant problems (low self esteem, damaged relationships, etc.)? It's hard to say, and doesn't really matter.
As with the codependent, the only cure for the dry drunk is embracing selfhood and relationships with a sense of meaning and purpose.