Final answer:
The term 'irresolute' accurately describes a person who is uncertain and indecisive, which aligns with the question's context of hesitancy and imperfect information.
Step-by-step explanation:
The word that best describes feeling or showing uncertainty; hesitant and indecisive is 'irresolute'. This adjective directly corresponds to someone who has difficulty making decisions or committing to a course of action due to uncertainty. In contrast, 'immaculate' refers to something that is perfectly clean or neat, 'immovable' characterizes something or someone that cannot be moved or persuaded, and 'illustrious' denotes well-known respect and admiration due to accomplishments. In the context of the examples provided, 'irresolute' aligns with the sense of being hesitant, having imperfect information, and possibly being in a state of detached contemplation.