This is the 7988th most frequent Russian word.
контактной
The Russian word "контактной" translates to "contact" in English, typically as an adjective, meaning relating to or involving contact.
Here, 'контактной' is used as an adjective describing 'линзу' (lens), specifying the type of lens.
Она приобрела новую контактную линзу.
She bought a new contact lens.
In this sentence, 'контактной' modifies 'сварки' (welding), indicating the type of welding method.
В их работе использовался метод контактной сварки.
In their work, a contact welding method was used.
Here, 'контактной' describes 'группы' (group), identifying the specific type of group (contact group).