verb trans
(+ with/to) to join or unite (oneself or another person or group) with, esp for common benefit
He allied himself with a wealthy family by marriage
(usu in passive) to combine with
(+ to) to relate (something) by resemblance or common properties
Its beak allies it to the finches
(+ with) to form or enter into an alliance
[Middle English allien via Old French from Latin alligare to bind to, from ad- + ligare to bind]