The most common and most likely answer to this crossword clue is the 6 letter word RUGOSE
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More clues leading to the result RUGOSE
Buddy explains!
The straight part
We know that "Covered with sunken lines" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case covered with sunken lines = rugose.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RUGOSE mean?
RUGOSE adjective- Having rugae or wrinkles, creases, ridges, or corrugation.
- Rugged, rough, unrefined.
- Having a rough, wrinkled, or wavy surface; commonly in parasynthetic usage e.g. rugose-veined or rugose-leaved.
- Describing a fossil coral of the extinct order †Rugosa (also called Tetracoralla), this order has horn-shaped corals with surfaces covered with ridges.
- Used when combined with another adjective, for example, rugose-reticulate or rugose-punctate.