This is the 5406th most frequent Russian word.
партией
"Партией" means "by/with the party" or "batch" (instrumental case of "партия").
The word 'партией' refers to a batch or shipment, specifically a group of items delivered together.
Он заказал новую партию товаров.
He ordered a new batch of goods.
Here 'партией' refers to a group within an orchestral or musical context, such as one instrumental section.
Музыканты играли в составе одной партии.
The musicians played as part of one section.
In this sentence, 'партией' denotes a grouping of parcels or letters sent together as part of a postal dispatch.