English
adstratum
From ad- + stratum.
Proto-Indo-European *h₂éd ‘near, at’
Proto-Italic *ad ‘toward, to, on, up to, for’
Latin ad ‘to, towards’
English ad-
Proto-Indo-European *sterh₃- ‘to spread’
Proto-Indo-European *str̥néh₃ti ‘to strew’
Proto-Italic *stornō
Latin sternō ‘spread’
Latin strātum ‘a spread for a bed, coverlet, quilt, blanket’
English stratum
Today it means
noun Any language having elements that are responsible for change in neighbouring languages
Language periods are conventional ranges, not dates for this word.
Etymograph / adstratum