INANELY

fatuously, inanely

(adverb) vacuously or complacently and unconsciously foolish

Source: WordNet® 3.1

Etymology

Adverb

inanely (comparative more inanely, superlative most inanely)

In an inane manner.

Source: Wiktionary

INANE

In*ane", a. Etym: [L. inanis.]

Definition: Without contents; empty; void of sense or intelligence; purposeless; pointless; characterless; useless. "Vague and inane instincts." I. Taylor.

– In*ane"ly, adv.

In*ane", n.

Definition: That which is void or empty. [R.] The undistinguishable inane of infinite space. Locke.

Source: Webster’s Unabridged Dictionary 1913 Edition