unswerving

going directly ahead from one point to another without veering or turning aside

• “some people see evolution as an undeviating upward march from simple organisms to the very complex”
• “a straight and narrow tree-lined road unswerving across the lowlands”

firm and dependable especially in loyalty

• “a steadfast ally”
• “a staunch defender of free speech”
• “unswerving devotion”
• “unswerving allegiance”