英语词源字典 - 在线词源网站

interlock (v.)[interlock 词源字典]: 1630s, from inter- + lock. Related: Interlocked; interlocking. As a noun, attested by 1874.[interlock etymology, interlock origin, 英语词源]
network (n.): "net-like arrangement of threads, wires, etc.," 1550s, from net (n.) + work (n.). Extended sense of "any complex, interlocking system" is from 1839 (originally in reference to transport by rivers, canals, and railways). Meaning "broadcasting system of multiple transmitters" is from 1914; sense of "interconnected group of people" is from 1947.
shelter (n.): 1580s, "structure affording protection," possibly an alteration of Middle English sheltron, sheldtrume "roof or wall formed by locked shields," from Old English scyldtruma, from scield "shield" (see shield (n.)) + truma "troop," related to Old English trum "firm, strong" (see trim).

If so, the original notion is of a compact body of men protected by interlocking shields. OED finds this "untenable" and proposed derivation from shield + -ture. Figurative sense is recorded from 1580s; meaning "temporary lodging for homeless poor" is first recorded 1890 in Salvation Army jargon; sense of "temporary home for animals" is from 1971. Related: Shelterless.