ectoderm vs rind

ectoderm

noun
  • Outermost of the three tissue layers in the embryo of a metazoan animal. Through development, it will produce the epidermis (skin) and nervous system of the adult. 

rind

noun
  • tree bark 

  • A hard, tough outer layer, particularly on food such as fruit, cheese, etc 

  • The gall, the crust, the insolence; often as "the immortal rind" 

  • An iron support fitting used on the upper millstone of a grist mill. 

verb
  • To remove the rind from. 

How often have the words ectoderm and rind occurred in a corpus of books? (source: Google Ngram Viewer )