an acutely pointed Gothic arch, like a lance
"The stained glass window features a lancet design that draws the eye upward toward the vaulted ceiling."
A sharp, pointed, two-edged surgical instrument used in venesection and for opening abscesses etc.
"The surgeon carefully inserted a sterile lancet into the patient's arm to draw blood before administering the vaccine."
To pierce with a lancet.
"The nurse gently pricked my finger with a sterile lancet to collect a drop of blood for testing."
A surname.
"The local history club recently held a meeting where they discussed the life of William Lancet, a prominent figure from the 18th century."