'estrechez' originates from Spanish, formed from the adjective 'estrecho' plus the suffix '-ez' (a suffix used to form abstract nouns denoting a quality).

'estrecho' derives from Latin 'strictus' (past participle of 'stringere', 'to bind/tighten'); through Vulgar/Old Spanish the form became 'estrecho', and the abstract noun 'estrechez' developed from that adjective.

Initially it meant 'tightness' or 'constriction' (a physical sense); over time it extended to mean general 'narrowness' and metaphorically 'scarcity' or 'lack'.