1. showing great enthusiasm for or interest in: an avid moviegoer. Synonyms: enthusiastic, ardent, keen; devoted, dedicated; zealous, fanatic. Antonyms: indifferent, apathetic; reluctant.
2.extremely desirous (often followed by for or sometimes of ): avid for pleasure; avid of power. Synonyms: eager; hungry, greedy, insatiable; covetous. Antonyms: disdainful, loath.
Origin: 1760–70; < French avide < Latin avidus, equivalent to av(ēre) ‘to crave’ + -idus
Avid, eager, keen all share the sense of strongly desirous. Avid suggests a desire akin to greed, so strong as to be insatiable: driven by an avid need for fame and recognition. Eager implies a desire that is strong and impatient but less than overpowering: eager to try his hand at new tasks. Keen carries a sense of zest and active, alert desire: an amateur painter, ever keen to try new techniques.
The word avid is relatively new, coming into the language in the 18th century from the French word avide, which comes from the Latin word avidus. That word, in turn, comes from the Latin verb avēre, a multifaceted word that is translated as “to crave, long for,” but incorporates many levels of desire, from eagerness to hunger to outright lust.
As used in English, the sense of physical craving or hunger is very rare, as in this 1866 translation of a line from Ovid's Metamorphoses: “Or dragon avid for his prey.” Instead, we tend to use avid synonymously with “intensely eager.” What avid lends to “eager” is the added dimension of intensification by either enthusiasm (an avid fan of indie films) or desire, which can sometimes morph into greed (avid for company; avid for gold). An excess of any of these qualities may lead to darker territories, as shown by this 1953 quote from The New Yorker: “He was writing for a public avid for gruesome details.”