Synonyms of the word

all-important

• adj. Very important; vital or crucial.

crucial

• adj. Being essential or decisive for determining the outcome or future of something; extremely important.
• adj. (archaic) Cruciform or cruciate; cross-shaped.
• adj. (slang, chiefly Jamaica) Term of approval, particularly when applied to reggae music.

essential

• adj. Necessary.
• adj. Very important; of high importance.
• adj. (biology) necessary for survival but not synthesized by the organism, thus needing to be ingested.
• adj. Being in the basic form; showing its essence.
• adj. Really existing; existent.
• adj. (of a lamination of a 3-manifold) Such that each complementary region is irreducible, the boundary of…
• adj. (medicine) Idiopathic.
• n. A necessary ingredient.
• n. A fundamental ingredient.

important

• adj. Having relevant and crucial value.