The word 'trustingly' is built upon the core concept of 'trust', which entered English from Old Norse traust, meaning confidence or firmness, itself derived from a Proto-Germanic root related to strength and consolation. The addition of the '-ing' suffix transforms the verb into an adjective ('trusting'), describing one who possesses or exhibits trust. Finally, the adverbial suffix '-ly', of Old English origin, is appended to form 'trustingly', specifying the manner of an action as being done with a trusting nature. This construction elegantly charts the word's evolution from a noun denoting a state of firm belief to an adverb describing the characteristic way such belief is demonstrated.

Structure: trust (to believe) + ing (adjective suffix) + ly (adverb suffix) - trust: From Old Norse traust (help, confidence, firmness), of Germanic origin. - ing: A suffix forming present participles of verbs, which can function as adjectives. - ly: A suffix forming adverbs from adjectives, meaning "in a specified manner".