considering; deliberating; thinking about it
Used when someone is in the process of thinking something over, often implying a decision has not yet been made. Common in phrases like 考え中です (I'm still thinking about it).
I'm still considering that proposal.
He seems to be thinking about something, and has been silent for a while.
Compound of 考え (thought, consideration) and the suffix 中 (in the middle of). The suffix 中 is productively attached to nouns to indicate an ongoing state or action.