in ‧ del ‧ i ‧ ble /ɪnˈdeləb ə l, ɪnˈdelɪb ə l/ BrE AmE adjective
[ Date: 1400-1500 ; Language: Medieval Latin ; Origin: indelibilis , from Latin indelebilis , from delere ; ⇨ ↑ delete ]
1 . impossible to remove or forget SYN permanent :
Her words left an indelible impression on me for years to come.
2 . indelible ink/pencil/marker etc ink etc that makes a permanent mark which cannot be removed
—indelibly adverb :
a moment indelibly imprinted on my mind