How many letters does the top answer for “casually thoughtless or inconsiderate” have?

The most common answer is offhand (7 letters).

Crossword clue: casually thoughtless or inconsiderate

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

offhand 7 letters wn-def

casually thoughtless or inconsiderate

offhanded 9 letters wn-def

casually thoughtless or inconsiderate

in a casually inconsiderate manner 50% similar → offhand, offhanded, offhandedly