{"era":"current","word":"keywords","meaning":"main search or index terms","children":[{"era":"1900s","word":"key + word","meaning":"crucial or essential words","children":[{"era":"pre-1100","word":"key","meaning":"device for opening locks","children":[],"language":"Old English"},{"era":"pre-1100","word":"word","meaning":"a unit of speech or writing","children":[],"language":"Old English"}],"language":"Modern English"}],"language":"Modern English"}