陆配 is Taiwan-specific shorthand for 大陆配偶 (dàlù pèi'ǒu — 'mainland spouse'). It sits alongside 外配 (wàipèi — foreign spouse, mostly Vietnamese/Indonesian) in Taiwan's immigration vocabulary, and is a regular politicized term in election cycles.
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Almost exclusively used in Taiwanese media, government documents, and political discussion. Mainland speakers would say 大陆配偶 or 大陆人配偶 in full.