IMPERCEPTIBLE

Too slight to be noticed (13)

Solution has appeared in 2 crosswords (1 across and 1 down):

• Quick crossword No 16,722 — 2023-12-09 00:00:05
  14A: Not visible (13)
• Quick crossword No 15,343 — 2019-07-10 23:00:40
  6D: Too slight to be noticed (13)