Assigning a meaning to the term 道 (dao or tao [both spellings are acceptable due to an oddity in the differences between the T and D used by English speakers and the appropriate consonant in contemporary 普通話 (pǔtōnghuà) = Mandarin) is extremely difficult. There are several reasons for this. First and foremost is that the meaning of 道 (dao) is part of the contested matter in early Chinese thought. In other words, the main schools are arguing about what [道] (dao) is. Why? At the simplest level, the character refers to a road or a path or a way. It also has other meanings such as to speak or to be the doctrine of a school of thought.
The question of whether the 道(dao) is a deity or something like that will vary depending on both the school of thought, the thinker, and the meaning of deity. I will start with the last question and work through the others depending on our definition. If we define a deity as a sentient being with particular personal thoughts, then I don't think any classical Chinese school of thought would have viewed the 道 as a deity.
If we define deity as the source of all power and the guiding force of reality, then I think that both Confucians and Taoists would believe this of the 道(dao) and it could be considered a deity. If we add to this definition a belief that this guiding force is guiding towards a particular goal, then we will still have the Confucians but not the Taoists as believing in a deity. This is because for Confucians the 道(dao) is guiding towards a well-ordered society in which the relationships are in harmony under the true sage king who has the mandate (命[ming]) of 天(tian). (More about 天[tian] later).
The Daoists are lost, because they don't see the world as having a productive trajectory. While the overlap is not perfect, there's definitely some anti-government thought going on in Taoism and the belief the harmony of the 道(dao) is already there and we just need to tap into it. Thus, one of the more famous parts of the 莊子(Zhuangzi) is a consideration of a butcher who is in contact with the 道(dao) and thus does not loose the sharpness of his knives because he cuts everything perfectly without thinking (無為 [wuwei]). So then, this could also be seen as a type of deity or at least a "spiritual energy" that a self can be in contact with.
Perhaps to qualify things a bit, the Daoists are not necessarily "lost", but the 道 gets you in touch with nature 然, but it's not at all clear nature has a direction or goal. If anything, many passages suggest either an endless cycle of recurring or some sort of joyous vibrant energetic chaos.
To simplify with a chart
Op: Omnipotent
Pe: Personified
GP: Guiding Principle
PS: Possessing Spirit
On: Omniscient
Bn: Benevolent
| Op | Pe | GP | PS | On | Bn
Christian God | ○ | ○ | ○ | ○ | ○ | ○ (omni?)
Greek gods | × | ○ | × | △ | × | ×
Dao in Daoism | △ | × | ○ | ○ | × | △ [not consciously]
Dao in Confucianism | △ | × | ○ | × | × | △ [not consciously]
Hegel's God | × |△ 1 | ○ 2| ○ | △3 | △4
1: God=us, 2: as Nessesity, 3: Eventually?, 4: if we are
The term also refers to schools that are built around trying to understand the "way" of something. Thus, 武士道 (bushido) = the way of the samurai [yes, its Japanese but the origin is the same].
So then in short the 道(dao) is a god to some but not to others. Definitely as Taoists mean it, it is no the Christian God, but they might want to have mystical encounters with it in the religious forms.
As promised, I will mention 天(tian). Part of why 道(dao) is not referring to a personal god is that 天(tian) might in fact be doing so. The history is long and complicated, but it looks like one very early Chinese dynasty believed in 天(tian) as their personal god. This people then got conquered by another dynasty who chose to usurp the authority of the first group. Thus, instead of just wiping out their gods, they actually chose to promote this deity and make it the "heavens" or a kind of fate like entity. Whether any scrap of belief in its personality remains is a matter of contest, but the majority of scholars think that by the time of Confucius, it was no longer conceived of as a personal deity (the minority view seems to be held primarily by religious thinkers like Kelly James Clark -- who is a Western trained philosopher rather than expert in sinology).
