thicken

verb

1. (transitive)To make thicker (in the sense of wider).
2. (transitive)To make thicker (in the sense of more viscous).

   “to thicken a sauce”

3. (intransitive)To become thicker (in the sense of wider).

   “As we age, the major arteries of our bodies frequently become thickened with plaque, a fatty material with an oatmeal-like consistency that builds up along the inner lining of blood vessels. The reason plaque forms isn’t entirely known, but it seems to be related to high levels of cholesterol inducing an inflammatory response, which can also attract and trap more cellular debris over time.”

4. (intransitive)To become thicker (in the sense of more viscous).
5. (transitive)To strengthen; to confirm.

   “And this may helpe to thicken other proofes,/ That do demonstrate thinly.”

6. (transitive)To make more frequent.

   “to thicken blows”

7. (literary)To make more detailed or comprehensive.