'Similar' is Latin 'similis' (like) — from PIE *sem- (one). The same root gave English 'same.'
Resembling without being identical; having a likeness or general correspondence.
From French 'similaire' or directly from Latin 'similis' (like, resembling, of the same kind), from PIE *sem- meaning 'one, together, alike.' This root is remarkably productive across Indo-European: Sanskrit 'sama' (same, equal), Greek 'homos' (same) and 'hama' (together), Latin 'simul' (together), 'semel' (once), and 'simplex' (single), Old English 'same' (same), and the prefix 'semi-' (half, partially). The PIE root *sem- encodes the concept