atomic behind the curtain behind the scenes camouflaged concealed corpuscular covered disguised embryonic evanescent germinal granular hidden impalpable imperceptible imponderable inappreciable indiscernible infinitesimal insensible intangible latent masked microcosmic microscopic molecular out of sight secret sightless subatomic submerged tenuous thin ultramicroscopic unapparent unappreciable unbeheld unbeholdable undetected undiscernible undisclosed undiscovered undivulged unexplained unexplored unexposed unnoticed unobservable unobserved unperceivable unperceived unrealized unrevealed unseeable unseen unsolved unspied untraced untracked unviewed unwitnessed veiled viewless