The term 'obtuse one' can be defined as someone who is not very intelligent. This term can be represented by three different crossword solutions: CRETIN (6 letters), DODO (4 letters), and MORON (5 letters). CRETIN is a derogatory term for someone who is mentally handicapped, while DODO is an extinct bird that was known for its lack of intelligence. MORON is another derogatory term for someone who is not very intelligent. All three terms are used to describe someone who is not very smart or has a low level of intelligence.