silicon (Si)
Chemical element Si; used in electronics, semiconductors, and materials science. The Japanese term ケイ素 is the native equivalent but シリコン is more common in everyday and technical contexts.
See also: ケイ素
Silicon Valley is the center of the IT industry.
This chip is made of silicon.
silicone (synthetic polymer)
Non-standard usage; シリコーン is the correct katakana for the polymer, but シリコン is often used informally for silicone products such as sealants, kitchenware, or implants.
See also: シリコーン
I used silicone for the bathroom caulking.
This baking mold is made of silicone.
Silicon is used in this semiconductor.
Silicone kitchen utensils are heat-resistant.