This is the 11786th most frequent German word.
tectus
The word "tectus" is not German; it is Latin and means "covered" or "hidden."
Here, 'tectus' means 'concealed', deriving its meaning from Latin.
Er hat sein wahres Wissen gut tectus gehalten.
He has kept his true knowledge well concealed.
In this sentence, 'tectus' is used as an adjective to describe secrets as 'hidden'.
Die tectus Geheimnisse wurden endlich enthüllt.
The concealed secrets were finally revealed.
This illustrates 'tectus' qualifying a noun ('Motive') to indicate something not openly known or expressed.