タバコ

シガレット sense 1
シガレット is a Western-style loanword for a cigarette, used mainly in formal or brand contexts, while タバコ is the everyday word for tobacco or a cigarette in general.
葉は巻まき
タバコ is the general word for tobacco or cigarettes, while 葉巻 refers specifically to a cigar made of rolled tobacco leaves.

Don't confuse with

煙けむりN3sense 1
タバコ (tobacco/cigarette) shares the kanji 煙 with 煙 (けむり, smoke), but they are read differently and mean different things—one is the product, the other the smoke it produces.
ニコチン
タバコ is the tobacco product or cigarette itself, while ニコチン is specifically the addictive chemical it contains, so learners often use the two interchangeably by mistake.
吸すい殻がらN1
タバコ refers to a cigarette itself (unsmoked or being smoked), while 吸い殻 is specifically the leftover butt after it has been smoked.

本ほんN5
Used for cigarettes or cigars, which are long thin objects, e.g. タバコ一本 (one cigarette).
箱はこN5
Used for cigarettes packaged in boxes/packs, e.g. a pack of cigarettes.

タバコUsage42%
Most common spelling; the word is usually written in kana.
煙草たばこUsage32%
gikun (meaning-based reading) or jukujikun
Kanji spelling; less common than kana but still encountered.
たばこUsage26%
gikun (meaning-based reading) or jukujikun
Hiragana spelling, also common.
莨たばこUsage<1%
rarely-used kanji formgikun (meaning-based reading) or jukujikun
Rarely used kanji form.
烟草たばこUsage<1%
rarely-used kanji formgikun (meaning-based reading) or jukujikun
Rarely used kanji form.

Borrowed from Portuguese 'tabaco'.