Shallow-of little depth
Mildred is indirectly characterized as Ignorant in "Fahrenheit 451". One example of this is how she stays home all day watching TV and listening to music all day long. Another thing that describes her ignorant is that she doesn't speak with Montag at home and she doesn't care about Clarisse's death. This is a indirect characterization because it doesn't explicitly tell us about Mildred, but we can gather this information based on the events in the story
Mildred was directly characterized as stupid. One example of this is when Mildred snatched the phone and said "the white clown's on tonight.' Then Montag steps in the kitchen, throws the book and says "you are really stupid". This is an example of direct characterization because the words are explicitly spoken; the audience does not have to gather clues to support the information either.