pondering
adj.thinking about something very carefully for a long time. You use this to describe someone who is deep in thought.
adj.engaged in deep, serious, or quiet reflection. Often used as a participial adjective to describe a person's state or facial expression.
“He sat by the window with a pondering look on his face.”
“After reading the difficult letter, she spent the rest of the afternoon in a pondering mood.”
“The philosopher remained silent for several minutes, his pondering expression suggesting that he was weighing the ethical implications of the question before providing an answer.”
Often follows linking verbs like 'remain' or 'seem', or modifies nouns like 'look', 'expression', or 'silence'.
“Liverpool are pondering a third bid for Brighton’s Yankuba Minteh while they continue to talk with Paris Saint-Germain over Ibrahim Mbaye and Barcola.”