1. Give a definition for the meaning of a word
   "Define ‘sadness’"
    
2. Determine the essential quality of
   "Scientists worked to define the characteristics of the new element";
   - specify, delineate, delimit, delimitate
    
3. Determine the nature of
   "What defines a good wine?"
    
4. Establish or state a specific value or set of values
   "define the parameters";
   - specify, set, determine, fix, limit
    
5. Show the form or outline of
   "The camera could define the smallest object"; "The tree was clearly defined by the light";
   - delineate

Derived forms: defining, defines, defined

Type of: ascertain, characterise [Brit], characterize, choose, determine, find, find out, pick out, select, show, take

Encyclopedia: Define, Measure, Analyze, Improve and Control