underseek
Underseek (verb) means to look into something carefully.
Etymology
Came into English via Middle English underseken, onderseken (also undersechen), which developed from Old English undersēcan (“to investigate, examine”), equivalent to under- + seek. It is cognate with West Frisian ûndersykje (“to research”), Dutch onderzoeken (“to investigate, probe, examine”) and German untersuchen (“to examine, investigate, explore”).