Godan verb with 'mu' ending, Intransitive verb
to be crowded; to be packed; to be busy
今ちょっと立て込んでいるので、後にしてもらえませんか。I'm tied up now. Could you make it later? to be piled up (of work); to be busy (with many things); to be packed (of one's schedule); to have a lot of work to do; to have one's hands full
Also written 立込む【たてこむ】