Please display the important parts in bold.
Bold headings are easy to read.
I made the important part bold.
Please write the heading in bold.
I emphasized the report's conclusion in bold.
太字 refers to thick, bold characters, while 細字 refers to thin, light characters, the direct opposite.
太字 means bold type (thicker strokes), whereas 斜体 means italic type (slanted characters); learners often mix up these two text-style terms.
Compound of 太 (ふと, 'thick') and 字 (じ, 'character').