Weakmindedly is an adverb that describes a lack of mental fortitude or a tendency to easily succumb to external influences. There are several synonyms for this word that can be used to express a similar sentiment. For instance, the word 'spinelessly' is often used to describe someone who lacks courage or determination. Other synonyms include 'timidly', 'indecisively', and 'vacillatingly', which all convey a similar sense of weakness and uncertainty. Additionally, the words 'gullibly' and 'naively' can be used to describe someone who is easily influenced or manipulated. These synonyms provide alternatives to express the same or similar ideas as the word weakmindedly.