How = Alas! or, O how! Hebrew. 'eykah = an exclamation of pain and grief, a wailing cry (preserved in Eng. "jackal"). The Massorah (App-30) points out that this exclamation is used by three prophets, concerning Israel:
(1) by Moses in her multiplication (Deu_1:12. Compare Lam_1:11);
(2) by Isaiah in her dissipation (Isa_1:21);
(3) by Jeremiah in her desolation (Lam_1:1).
This word "How" is to be supplied at the beginning of verses: Lam_1:2-3 by Figure of speech Ellipsis (App-6). Compare also Lam_2:1; Lam_4:1; and Isa_14:12.
solitary: i.e. empty; referring to the houses and streets.