| invisible(adjective, knowledge, hidden, unable, imperceptible) |
| imperceptible(adjective, knowledge, invisible) |
| impalpable(adjective, knowledge, imperceptible, unsubstantial, intangible) |
| inappreciable(adjective, knowledge, imperceptible) |
| indiscernible(adjective, knowledge, imperceptible, invisible) |
| intangible(adjective, knowledge, indefinite, imperceptible, obscured) |
| insensible(adjective, knowledge, imperceptible) |
| imponderable(adjective, knowledge, imperceptible) |
| unnoticeable(adjective, knowledge, imperceptible) |
| camouflaged(adjective, invisible, latent) |
| concealed(adjective, invisible, latent) |
| covert(adjective, invisible, latent) |
| inconspicuous(adjective, imperceptible) |
| indistinguishable(adjective, knowledge, imperceptible) |
| latent(adjective, invisible, latent) |
| unapparent(adjective, invisible, latent) |
| hidden(adjective, invisible, latent) |
| buried(adjective, latent) |
| evanescent(adjective, imperceptible) |
| indistinct(adjective, imperceptible) |