acicular vs pencil-thin

acicular

adj
  • Needle-shaped; slender like a needle or bristle. 

  • Of a leaf, slender and pointed, needle-like. 

  • Having sharp points like needles. 

pencil-thin

adj
  • Somewhat cylindrical and slender like a pencil; also, tall and thin. 

How often have the words acicular and pencil-thin occurred in a corpus of books? (source: Google Ngram Viewer )