高まる
たかまる · takamaru · JLPT N3 · verb-godan
to grow
📈 高 taka(i) = high + -maru = becomes high by itself
高まる comes from 高い takai, high. The -maru ending marks an intransitive verb: something rises on its own, like tension or expectations. Its transitive partner is 高める takameru, to raise something, so -meru means you do it and -maru means it happens.
高 — pictograph of a tall building/tower
高 is a pictograph of a tall structure, likely a watchtower or multi-story gate, with a roof on top, an upper chamber, and a base below. From this concrete image of height it extended to the general meanings 'tall,' 'high,' and figuratively 'lofty' or 'noble.'