The Etymologies of the 1930s had N. iant “yoke” derived from primitive ᴹ✶yantā under the root ᴹ√YAT “join” (Ety/YAT). Deleted forms iad and [?]iannas were written immediately after it (EtyAC/YAT). In Tolkien’s later writings S. iant was translated as “bridge” (SA/iant; SD/129; WJ/333), as opposed to N. ianw “bridge” from The Etymologies (Ety/YAT).
Conceptual Development: The Gnomish Lexicon from the 1910s had G. galt “yoke” with cognate ᴱQ. yalte (GL/37), which was probably derived from the early root ᴱ√YḶTḶ from the contemporaneous Qenya Lexicon which also had ᴱQ. yalta “yoke” as a derivative (QL/106). In Gnomish of the 1910s ancient initial y became g, which explains G. galt vs. ᴱQ. yalta.
Neo-Quenya: For purposes of Neo-Sindarin, I would revise G. galt to ᴺS. ialt “yoke” as a cognate to ᴺQ. yalta, since S. iant is used for “bridge”.
It originally meant "bridge" in the Etymologies, but was apparently switched with iant