alike adj. (now almost always used predic.). OE. ġelīċ (ME. ilich(e), ilik(e); a-forms from XIV) :- Gmc. *ʒa- Y- + *līkam form (see LIKE2); for the development of OE. ġe- to a- cf. AFFORD, AWARE. Cf. LIKE1.
So alike adv. OE. ġelīċe. In ME. both words were prob. infl. by ON. adj. álikr, adv. álika and corr. OE. onlīċe, ME. anlich(e), in which the pref. is Gmc. *ana- (see ON).

a·like / əˈlīk/ • adj. (of two or more subjects) similar to each other: the brothers were very much alike the houses all looked alike.• adv. in the same or a similar way: the girls dressed alike in black pants and jackets. ∎  used to show that something applies equally to a number of specified subjects: he talked in a friendly manner to staff and patients alike.