ralju -ral- gismu

x₁ is principal/chief/leader/main/[staple], most significant among x₂ (set) in property x₃ (ka).

Staple (= ralselpra); general/admiral/president/principal leader (= ralja'a, ralterbe'e; use additional terms to distinguish among these); also primary, prime, (adverb:) chiefly, principally, mainly; (x₂ is complete specification of set). See also vajni, te bende, minde, lidne, jatna, jitro, gidva, midju.

jbovlaste

In notes:

bende: x₁ is a crew/team/gang/squad/band of persons x₂ directed/led by x₃ organized for purpose x₄.
gidva: x₁ (person/object/event) guides/conducts/pilots/leads x₂ (active participants) in/at x₃ (event).
jatna: x₁ is captain/commander/leader/in-charge/boss of vehicle/domain x₂.
jitro: x₁ has control over/harnesses/manages/directs/conducts x₂ in x₃ (activity/event/performance).
lidne: x₁ precedes/leads x₂ in sequence x₃; x₁ is former/preceding/previous; x₂ is latter/following.
midju: x₁ is in/at the middle/center/midpoint/[is a focus] of x₂; (adjective:) x₁ is central.
minde: x₁ issues commands/orders to x₂ for result x₃ (event/state) to happen; x₃ is commanded to occur.
vajni: x₁ (object/event) is important/significant to x₂ (person/event) in aspect/for reason x₃ (nu/ka).
ra'u: discursive: chiefly - equally - incidentally.
kagytruralju: r₁ is CEO (Chief Executive Officer)/MD (Managing Director) of company/corporation/firm t₂=k₁.
raldargu: x₁ is a highway to x₂ from x₃ with route x₄
raltca: x₁ is a/the capital of x₂.
raltu'a: x₁ is the mainland of x₂
ralxelbo'a: r₁ is the frequency of the carrier wave of signal b₁.
truralju: r₁ is the head-of-government of polity t₂.
protagonista: x₁ is a/the protagonist/main character/primary personal figure in narrative/story/enterprise x₂