to get in touch with; to contact; to stay in contact (with); liaison; (math.) connection

federal; federation; commonwealth; federal union; federal state; union

alliance; union; coalition

Soviet Union, 1922-1991; abbr. for Union of Soviet Socialist Republics (USSR) 蘇維埃社會主義共和國聯盟|苏维埃社会主义共和国联盟[Su1 wei2 ai1 She4 hui4 zhu3 yi4 Gong4 he2 guo2 Lian2 meng2]

to combine; to join; unite; alliance