Glamour ("Glamarye" in the original Polish) is an ointment-like magical cosmetic which smells of lilac and gooseberries and makes a "dazzling impression". It is applied around the eyes and essentially bedazzles anyone who gazes upon the wearer. Yennefer used it when she and Ciri first entered Gors Velen after leaving Ellander.
In the short story "Coś się kończy, coś się zaczyna", Triss makes a batch of it for all the female guests at Geralt and Yennefer's wedding. Unfortunately for the halfling women, it seems glamour does not work for them at all.