while; even though; despite~
A formal conjunction meaning 'while' for simultaneous actions or 'even though' for contrast, used in written and formal speech.
つつ has two main uses. The first is like 'while' in English, describing two actions happening at the same time by the same subject. For example, you might say you think about someone while walking. The second use is 'even though' or 'despite', expressing that something is true but you act against it. For instance, you know it's bad but you still do it. Both uses are formal and belong to written language, such as novels, essays, or news. In casual conversation, you'd use ながら for 'while' and のに or けど for 'even though'.